Hello people of Reddit,
I am planning to upgrade from my Intel Core i7-4790K to an AMD Ryzen 9 3900X very soon (I will not wait for 4th gen Ryzen!) and I have been browsing the web regarding this CPU and Ryzen over all. Benchmarks clearly show that AMDs CPUs outperform Intels CPUs not only in price/performance but also in high end performance too.
But I have come across the term "infinity fabric" regarding RAM speeds. As I understood it you want to keep the ratio between infinity fabric clock and RAM clock as simple as possible so 1:1 would be the most optimal but since the infinity fabric clock cant get much faster than 1900MHz when overclocking it at least for the Ryzen 3000s. Most people say that 3600MHz is the optimal RAM speed for Ryzen and can increase performance dramatically. Obviously the infinty fabric should be clocked at 1800MHz if we use 3600MHz RAM so we at least get a 2:1 ratio, which both yields high RAM speeds but also has a really simple infinity-fabrick-clock/RAM-clock-ratio rather than a 209/234-ratio.
Now since going for 3600MHz RAM seems to be an obvious choice how about voiding warranty? AMD claims their R9 3900X can handle RAM speeds up to 3200MHz. Since using 3600MHz RAM would mean that I use my CPU outside of the manufacturers specs this should void my warranty which could be quite important too keep at least for the first few months.
Now my 2 questions:
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Regarding Linus Tech Tips (https://youtu.be/iHJ16hD4ysk?t=436) 3600MHz is the best choice for performance - while exceeding the manufacturers specs - does this void warranty or do I need to do driect canges to my CPU to void the warranty?
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How realiable is running 3600MHz RAM on a 3rd gen Ryzen in the first place?
Thank you for reading till here, I really appriciate your help.
Regarding your question, I run a R5-3600 with 3600MHz ram overclocked to 3900MHz with infinity fabric (or sometimes your bios lists it as FCLK) clocked at 1900MHz.
DDR4 is Double Data Rate, and DDR memory can send and receive signals twice per clock cycle.
In English, that means that the listed spread of your ram is double the actual frequency- DDR4-3600 would be running at 1800MHz, DDR4-3733 would be running at 1867MHz, and so on. So you are still getting a 1:1 ratio between RAM speed and Infinity Fabric speed, even if your RAM speed is greater than 3600MHz, but sometimes a manual infinity fabric overclock is required in the bios, or in AMD Ryzen Master. I personally prefer the bios option.
So if I can run 3800MHz ram and 1900MHz FCLK on a Ryzen 5, 3600MHz ram on a Ryzen 9 should be no problem. And RAM needs to be overclocked to reach its rated setting anyway- for instance a kit of DDR4-3000 would be running at 2133/2400/2666MHz out of the box, and would require an XMP/D.O.C.P overclock to actually reach 3000MHz. After that you work your way up from their finding your highest stable overclock- I personally couldn’t get past 3866MHz at 1:1 between FCLK and MCLK without a blue screen and restart.
just made the switch myself. Overclocking is quite different from intel. I have actually decided against any cpu overclock. With the new amd stuff, to overclock you use PBO (precision boost override) This does overclock the processor, but all the cores, at a fairly high voltage, all the time, for a much better multi threaded speed. But at a high cost. You actually loose performance on lighter tasks (read gaming) as the processor would be able to self overclock (at stock) single cores at higher speeds. Then there is temperatures. Stock settings allow it to down volt and underclock constantly. Overclocked is high voltage all cores full time. And chip degradation. You can slowly cook these things with even "mild" over clocks.
If you need better multi threaded performance, over clocking is useful, but you would be way better off getting more cores instead.
As for memory speeds, I do run 3600mhz with no changes other than enabling xmp (D.O.C.P really) with a 1:1 ratio. This does not require a cpu overclock. This ram was on the QVL list for my motherboard at its rated speed.
Hey all:
This is really for my own information more than anything else; I don't have a pressing technical problem, but this issue has bothered me intellectually for some time, and I can't seem to find any articles that directly addresses it (maybe I'm just not searching for the right terms).
What determines the capacity, speeds, and populated slots that a given Ryzen CPU can support, and why? For example, it is commonly repeated that as you go up in total RAM capacity (from 2x8 to 2x16), you can expect your supported speeds to drop, and you may even need to loosen your timings. Why? This is doubly compounded if you go to even larger capacities or more physical sticks of RAM (2x32, 4x16, etc). Dual rank and single rank chips seem to play a role in this as well, but I'm not sure *what* role they play, only that the rank seems to matter. Does memory rank matter? If so, why?
I've heard it said that because the memory controller is onboard the CPU (Infinity Fabric), it's really the quality of your silicon that determines your luck with memory capacity, speed, and timing. Is this true? I've also read that your motherboard's power delivery can make a big difference too (though I'm not sure why that would be the case; RAM is, to my knowledge, not a substantial source of power draw). Does that also play a role? How and why?
Memory support/performance appears to have improved with each successive generation of Ryzen (Zen was the most finicky, Zen+ had major improvements in RAM compatibility, Zen 2 was even better, etc), but I still don't grasp the nuance (or the rationale) behind how these four RAM variables--speed, capacity, timing, # of sticks--are influenced by the CPU and/or motherboard. Any insight would be greatly appreciated.
EDIT: Thank you all for your responses thus far; this has been highly educational! I have some more reading to do, but now I understand what sorts of things I need to google in order to better understand.
Hi everybody,
I'm super new to this new amd exciting world of over clocking.
My rig is a 7800x3d on a asus b650e-f with 6000mhz at 32gb.
I just downloaded OCCT and I had noticed my IF (infinity fabric) is running at 1796mhz.
To point out, my bios has been updated and my bios setting is base outta the box with expo off.
My question is if my memory speed is actually 3000mhz, and the IF only handles half that, is it possible to running my ram kit at the 1796 or what ever bios setting allows close to this number, will it be stable?
This is all theory, let's talk about it!
Computer Type: Desktop
GPU: Powercolor Hellhound 7900XTX
CPU: RYZEN 7800X3D
Motherboard: ASRock B650 Livemixer
BIOS Version: The latest one off their website as of yesterday
RAM: 32GB G.Skill 6000MT/s DDR5
PSU: Corsair RM1000x
Case: Coolermaster
Operating System & Version: WINDOWS 11 Pro
GPU Drivers: 23.10.2
Description of Original Problem: I have enabled XMP on the RAM to run at the advertised 6000MT/s and my understanding is the infinity Fabric should ideally be half this. However when I set it to 3000 the PC won't post and I have to reset the CMOS to get it to POST again.
Troubleshooting: Ive read a bit on the infinity Fabric being a little unstable on these higher speeds - I was wondering if it is better performance wise to run the RAM at 4800MTs instead and keep the infinity Fabric at 2400 where it seems happy to run, or still run the RAM at XMP with the infinity Fabric not running at its optimum ratio?
With DDR modules now reaching 4000+Mhz, would it be feasible to start setting IF at a 1/3 speed, vs 1/2 of the ram? Eg: On 3600Mhz RAM running IF at 1200Mhz vs 1800? I have 1 ryzen 3900x, and 1x 3950x that don't reach to 1800Mhz infinity fabric. The system just simply won't boot at those settings.
So I was thinking if there would be any performance benefit running IF at eg: 1500Mhz instead of 1800Mhz, when RAM speeds reach 4500Mhz?
For zen and zen + the fabric runs at the actual ram speed, aka half of the ddr speed. so 3200mhz ddr4 makes the infinity fabric run at 1600mhz. I know theyve said uber fast ram will work now the infinity fabric will just slow down to half speed to be stable. ie 800mhz if 3200mhz ram made it slow down(which i doubt it will).
Have they said what that speed will be though? like in a lot of non memory bandwidth intensive situations(like games) it could make a cpu with 3200mhz ram run the application faster than say 4400mhz ram or really anything under 6400mhz ram which doesnt exist yet. I'll need to upgrade ram when i get a 3950x but im a bit weary if I go too ham on it the more expensive ram could make my cpu perform worse than cheap ram.
In auto, after the 3733 multiplier.
However, you should be able to set the frequency manually in the new Infinity Fabric frequency / timings menu.
at 3866 it will run at half speed. source: https://cdn.sweclockers.com/artikel/bild/72065?l=eyJyZXNvdXJjZSI6IlwvYXJ0aWtlbFwvYmlsZFwvNzIwNjUiLCJmaWx0ZXJzIjpbIndtIiwidD1vcmlnaW5hbCJdLCJwYXJhbXMiOltdLCJrZXkiOiIzOWMzZDdhOGUyZTRiMjI2MzU2OTI3YTJkZGQ4ZGJmYSJ9
Hi, I'm going to build my new PC and I'm thinking about Ryzen 3. I know that RAM speed is very important because of infinity fabric (speed of CPU depends on speed of RAM) but when i was emailing with asrock support about ram vendors they had send me that info:
"the memory controller is integrated in the CPU, and runs at 2667MHz at default settings. 300MHz does not make any difference in the overall performance, only a memory benchmark will show better results, but for the performance it doesn't make a difference, because the speed of the CPU will stay the same."
Is this true and in non extremal application (recreation gamming) I won't see noticible difference between 2666 and 2933 or 3200 ( or difference will come from only the RAM itself but not longer from the cpu) ?
Out of the box, it's 2133 and not 2667. 2667 is the maximum supported RAM speed.
300MHz does not make any difference in the overall performance, only a memory benchmark will show better results, but for the performance it doesn't make a difference, because the speed of the CPU will stay the same."
It's so wrong it hurts. There are plenty of benchmarks to see the actual results (I did some as well) and the message is clear. Get fast RAM. I mean going from 48 to 55 mins at Fallout or from 70 to 78 in CIV6 are pretty telling and not what you'd call "memory benchmarks".
The higher the memory speed the higher the performance period. Faster memory means faster performance, ignoring the infinity fabric.
The Ryzen 3 chips are 2+2 if I remember correctly, meaning unlike the 4+4 Ryzen 7 chips, you get 2 less cores in each CCX. (instead of just going 4 core ccx and disabling the other ccx) So, technically a higher IF speed would result in more performance, especially in games that use more than 2 cores.
Higher memory speed comes with lower minimum fps and higher maximum fps. Unlike Intel where usually, memory speed don't mean shit.
I run 3200, I wouldn't imagine running anything less. In my own tests, I get a noticable difference between 2666 and 3200 in games, and in every application really.
EDIT: They probably don't want to get your hopes up, as results vary, as everything does in the computing segment.
I have a Ryzen 3700x running on an AsRock X570 Steel Legend with 2x 8GB sticks of 3600 MHz Corsair Vengeance RGB Pro memory (CMW16GX4M2Z3600C18).
When I first installed the sticks, I remember quite clearly setting up the XMP profile. However, I recently checked and saw they were running at a mere 2666 Mhz. Both sticks are in the correct A2 and B2 slots.
Now, for some reason, the XMP profile will simply not work and the sticks default to 2666 Mhz. Whenever I try the 3600 MHz XMP profile, my rig won't post and gets stuck in a boot-loop. I've tried a number of fixes.
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I tried updating the BIOS - Currently running 3.50. Updating has not solved the problem.
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I tried manually inputting the memory speed and timings using DRAM calculator. This did not work. Still won't post.
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Upon attempting other memory speeds, I found I can get my rig to post any speed up to 3400 mhz. However, upon further testing - 3400 MHz is not stable.
I stumbled upon another reddit post discussing Infinity Fabric in relation to memory speeds. One user claimed setting IF to 1500 fixed his issues. I tried this and SURPRISE - my rig posts and shows both sticks running at 3600 MHz!
I don't know a lot about FCLK/MCLK/UCLK - I've been seeing these acronyms a lot and I'm reading up on them. My understanding is that for Ryzen, these should all be set to a 1:1 ratio with memory. Meaning IF should be set to 1800. However, I can't get a post at 1800.
I'm going to launch into Windows from my successful post and see how stable RAM is, but I'd appreciate some help/insight into this!
Thanks :)
EDIT #1: I should also mention I have checked the MOBO's qualified vendor list and my RAM kit IS supported.
EDIT #2: I found another reddit post which really answers my question. It appears there's a lot of misinformation online. Many of the posts you'll come across on forums say 3rd Gen Ryzen CPU's should be able to run Infinity Fabric at a 1:1 ratio with memory speed. Meaning, if you have a set of DDR4 3600 MHz memory, you should set your IF speed to 1800. HOWEVER - it seems that this is largely dependent on both the silicon lottery and what CPU you have. For instance, according to this post,
https://www.reddit.com/r/Amd/comments/cug803/3rdgen_ryzen_infinity_fabric_may_not_reach_1800mhz/
the 3700X's standard frequency is 3200Mhz, so setting the IF frequency over 1600 is considered overclocking.
Funny enough, after successfully posting an IF frequency of 1500 (and knowing I had already failed to post at 1800), I tried(and failed) to post at 1700. Then successfully posted at 1600 and found the reddit thread explaining all this. LOL.
THE BIG QUESTION I HAVE - Why do I have to manually set my IF frequency for my XMP profile to work? Because If I set IF to AUTO (which is the default bios setting), my XMP profile WILL NOT POST. So is the AUTO function just broken?
Ok, so you always hear about the 'AMD sweet spot' for memory speeds, with 3000MHz (6000MT/s DDR5 speeds) memory controller clocks (UCLK) and 2000MHz infinity fabric clocks (FCLK) being ideal to "minimize latency" in your system memory. When this first became a thing, it was suggested that once memory speeds got fast enough, it would overcome any latency introduced be running the UCLK at 1:2, but in the early days of Ryzen it wasn't clear how fast the memory needed to be to cross that threshold. With improvements to the memory compatibility in Ryzen 7000/8000/9000, I had seen that gap closing quickly and finally decided to do some controlled testing at different memory speeds to find out if it was worth running faster memory speeds than the 'AMD sweet spot' suggests.
Using my 9600X system running memory configurations at 7800MHz (uclk=fclk at 1950MHz) , which were tested against 6000MHz CL28 (uclk = 3000MHz and fclk = 2000MHz), with some bonus tests done with 6000MHz CL28 with uclk at 1500MHz, while sprinkling in some others too just for extra comparisons. To do this testing, I made a few profiles in bios where all settings were the same except the memory speeds/timings, and also one profile which is my current daily profile for this system with memory at 7823cl34 and tighter timings overall. Test systems were one of two identical Asus X670E-i motherboards and using twin kits of 2x24GB Patriot Extreme 5 8200cl38 DDR5:
2x Asus X670E-I motherboards and 2x24GB DDR5 8200cl38 kitsALL 7800MHz CONFIGURATIONS WERE TESTED FOR STABILITY PRIOR TO TESTING PERFORMANCE:
7800cl38 VT3 2.64hrs 7800cl34 VT3 108minutes Karhu 11.5hrs (~16000%) 7800cl38 Karhu for 6.5hrs (9000+%)I wanted to use 7800cl38-46-48-40 and 7800cl34-45-45-39 as two comparisons at least for a few tests just to see what differing quality RAM kits would offer compared to a tight 6000cl28-38-38-36 kit. Looking at a quick AIDA64 comparison:
AIDA64 memory benchmark for 6000cl28, 7800cl38, and 7800cl34The very first 6000cl28 screenshot was for a run where I realized I had the CPU boost set to negative instead of positive, which I corrected for the rest, but I included that result anyway just for fun. At 6000cl28, the measured memory latency was ~60ns, with 0.7ns/2.5ns/11.2ns latency for L1/L2/L3 cache respectively. 7800cl38 saw memory latency ~57.3ns with 0.7ns/2.5ns/9.7ns for L1/L2/L3. 7800cl34 improved memory latency to ~55.9ns. In true AIDA64 fashion, the measured read/write/copy speeds were a bit up and down, but in general it would seem the faster memory speeds offered minor improvements across the board.
"MaxOC" 7823cl34-45-45-39 saw some additional improvements:
7823cl34As an additional test for memory latency, passmark Memory Mark was ran with a few different memory speeds, including once with 6000cl28 at uclk=1500MHz, to compare the measured memory latencies using a different test:
6000cl28 7800cl36 7823cl34 6000cl28 uclk=1500MHzWith the measured latency at 6000cl28 being 42ns, and 44ns when the uclk was halved to 1500MHz. 7800cl36 improved latency to 40ns and a "maxOC" 7823cl34 measured 39ns.
3DMark CPU profile was up next:
6000cl28 7800cl34This test had 7800cl34 performing very slightly better for when more than half the CPU threads were loaded, and about the same on lightly threaded workloads.
I went with Ycruncher 1B to see if there was much difference seen there, and 6000cl28 with uclk=1500MHz was again included as an additional comparison:
6000cl28 7800cl36 7800cl34 7823cl34 6000cl28 uclk=1500MHzThough the halving of the uclk only saw 0.27% higher time, the tightest timings on high speeds only saw a 0.82% faster time, though there were consistent improvements as tighter timings were tested.
SuperPI saw very similar results:
6000cl28 7800cl34 6000cl28 with uclk=1500MHzIn this test, halving the uclk at 6000cl28 increased the time by 0.74% where 7800cl34 was 0.50% faster.
To keep this post from going on and on, I will put some more general CPU performance results such as gaming tests in a separate post, but I find these results are pretty interesting already. In summary I would conclude that while 6000cl28 with fclk=2000MHz and uclk=3000MHz is certainly faster than 6000cl28 with 2000fclk and 1:2 uclk=1500MHz, it is somewhat equivalent to 7800cl38 at 1:2 with fclk=uclk at 1950MHz, and starts to fall behind when compared to 7800cl36 at 1:2 with fclk=uclk at 1950MHz. Then the gap widens more with 7800cl34 and 7823cl34 etc.
I'm already pretty deep down this rabbit hole so I'll see where it goes.
Before anybody jumps to weird conclusions, I need a disclaimer that I am not trying to justify the purchase of Ryzen 9000 compared to previous generations, I am not mentioning any performance compared to any of the team blue CPUs, and I am not personally attached to any platform nor was any hardware tested here provided for free by any PC hardware companies. I was simply tuning a 9600X system to learn more about it and taking the time to share some interesting results with anybody who would also be curious to see :)
Hey everyone. 5900x, 32gb 3200mhz CL14 B-die. I've been noticing some weird stuttering/issues with my system as of late. I was thinking that maybe I needed to upgrade to 3600mhz to get that coveted 1:1 FCLK but I wasn't sure if I needed to spend that money after doing some digging. Some have said online that if I'm running 3200mhz that I should drop my FCLK to 1600? I believe it's set to auto currently but I thought maybe it being set to that wasn't correcting to the best ratio? Would I see a performance change with it being 1:1 with my 3200 or are there only diminishing returns after 1900+? Also, I've also read that hard setting core speeds could be bottlenecking my single core performance due to the default auto enhancement allowing the chip to properly boost when needed. I have substantial cooling but was turned off of the auto-enhancement due to it making my 8700k burn like thermite in a cardboard box, maybe it's better on 5000 series? Thanks for any help.
I am a bit confused on the "coupled" term used. Other than that I know I want to get the 1:1 ratio.
[Not sure if I should be asking this here or over at overclocking]
I am really interested in this Infinity Fabric but I have not "digesting" what I have been reading and re-reading.
Ryzen 3900 stock settings with AIO
x570 Aorus Ultra
4133 Patriot Steel Ram
Everywhere I see is 3600 ~ 3733 for the Infinity Fabric to be 1:1.
I read around June/july that 3733 was "a guess" based on Overclocking.
Anyways did some RAM tests [about 10 runs of Nova bench each 3 minutes after startup]
3733 16-15-16-16-34-50 runs about 5% slower
40580 MB/s
vs
42580 MB/s
3600 16-15-15-34-50
[I hope I am asking this correctly]
Did my speeds cause the IF to go over the 1:1 ratio?
Or do I need to turn on coupled mode and move my IF to match the ram speed?
[I am happy with my performance, but I don't want to be leaving 5% performance on the table]
Any information on coupled or IF speeds would be greatly appreciated.
I think when you go above 3600 you have to manually set the infinity fabric speed to match the memory speed. So its possible the reason you have lower scores at 3733 is because the IF is now running in 2:1 mode rather than 1:1.
Try the 3733 speed again this time with the IF speed set to 1867 to match the memory speed.
If you run 3733 ram set your infinity fabric (fclk) to 1867
With that kit of ram you could run 3800 with fclk at 1900 if your cpu is capable, not all ryzen 3000 CPU’s can hit 1900 fclk though (silicon lottery)
Hi guys,
Do I still need to put the infinity fabric at 1800mhz when ram is at 3600mhz? Or auto is now working fine?
Thank you.
I'm using a Ryzen 5800x and 4133MHz CL18 memory, which is above what is called "ideal" for this generation of Ryzen.
Would I achieve better performance by slowing down my memory down to achieve 1:1 Infinity Fabric ratio?
I'm lost in the hyperfocus sauce.
Across the board on here, the majority of recommendations for RAM timing on AM5 are 6000mhz CL30 because it's "the sweet spot for AM5" or "it's the most stable" or "AM5 only officially supports up to 6400" or "once you pass 6000 you break the 1:1 infinity fabric"
But then I'm leaning about AGESA and how a recent 1.0.0.7c version has let people get to 1:1 with 6400 and it seems like people are trying to achieve 1:1 with higher clock speeds? And now 1.1.0.0 is out as of a few days ago and I'm curious what people are doing with that too.
Which leads me here to ask if all the recommendations from basically the past year are based on old AGESA and are people just parroting what they've also been reading. If people are getting 1:1 with 6400, is 6400 the new recommendation? If 6400 is the new recommendation, will 6800 ever be the new recommendation? If these new AGESA versions start making faster RAM stable, then should I just buy 7200 CL34 Hynix A die from G. Skill for only $15 more than 6000 CL30 and underclock it to 6400 for the time being, until 7200 is stable 1:1?
I picked up the 7800x3d and I know the x3d doesn't care about mem frequency as much, but still deep dove and I can't get out lol
(Not sure if necessary but here’s my specs) Ryzen 9 3950x, X570 Aorus Master, Trident Z Neo 4x8GB 3600mhz, Corsair AX850 Titanium
My ram isn’t being stable when i enable xmp so im trying to manually set it to 3200 at 1.35v to see if that’s better (and if i just got bad luck on a memory controller.) I understand that the infinity fabric should be about half of the mhz of the ram, but I’m unclear on if i need to adjust voltages or anything like that when manually setting infinity fabric. Or does even leaving it on auto set the correct speed? Any tips would be great!
AMD has long been advertising that the recommended RAM speed of 3rd-gen Ryzen is DDR4-3600 with a 1:1 infinity fabric frequency (1800MHz). It seems that cranking the IF up to 1900MHz would need some luck, but most people are doing the recommended 1800MHz with no problem.
However my 3700X cannot even hit the 1800MHz IF clock. I only saw very rare cases reporting the same problem (one in AMD forum, another in the tech support megathread here, all using DDR4-3600 and X570 mb), but seems like such a "worst case" scenario does exist. It is very frustrating that you pay the same price as everyone else but can't get the same performance, so I'm posting this thread to let more people aware of this issue.
I called AMD tech support this morning, and the rep said that the standard memory frequency of 3700X is DDR4-3200 so setting the IF anywhere above 1600MHz is overclocking. I didn't see this information from anywhere in discussions or reviews about 3rd-gen Ryzen processors, and perhaps it doesn't completely agrees with what AMD advertises.
I also wonder if in this case, my best bet is to just get the processor replaced, or I could underclock my RAM (3600 CL16) and tighten the timings to get the roughly same performace as the "standard" 1800 IF clock.
I called AMD tech support this morning, and the rep said that the standard memory frequency of 3700X is DDR4-3200 so setting the IF anywhere above 1600MHz is overclocking. I didn't see this information from anywhere in discussions or reviews about 3rd-gen Ryzen processors, and perhaps it doesn't completely agrees with what AMD advertises.
This is all over product documentation. For example:
https://www.amd.com/en/products/cpu/amd-ryzen-7-3700x
System Memory Specification 3200MHz
The slide the whole "sweet spot" thing originated from was clearly overclocking- I mean the ram speeds listed went way above what they officially support (4400 on the chart), and even said on the bottom of the slide, "memory overclocking not supported by AMD product warranty"
What the rep said would be correct. I don’t think they are going to do anything to help you directly. A lot of it is silicon lottery and luck.
TL:DR - I re-synched my IF at the 1:2 ratio which is the only other option my motherboard shows for Infinity Fabric to Memory Clock synchronization, the other option of course being 1:1. This allowed me to increase my RAM speed beyond the 3800 MT/s at 1:1 IF I'd been running for a few months now to see if I could get the RAM speed to be higher enough to overcome the latency penalties inherent in doing so, and then to see how different programs respond to that tradeoff. The former is now complete, the latter is ongoing.
Discussion: The conventional wisdom in AMD land is that for best performance the Infinity Fabric must always be 1:1 synched with the memory clock. "Everyone knows this!" We see this being said all the time, even used as a club in certain discussions in lieu of presenting actual data. After watching a Buildzoid video on Youtube a while back where he discussed this, and pointed out that if you can set your memory speed higher enough with de-synched (or rather synched at a worse ratio) IF it could still be an advantage to do so despite the higher latency.
I finally got around to trying this out. After ensuring I had my current bios profile safely stored off on a USB stick, I reset all my secondaries and tertiaries to Auto, reset my primaries to very sloppy settings up in the low 20s, and then started jacking up the memory clock. I booted successfully at 4266MT/s but failed to boot at 4400MT/s so I stopped at 4266. I didn't try any shenanigans to see if I could goose the machine into booting at 4400MT/s or higher with some more twiddling, so it's possible that through some further playing around those higher speeds could be achieved.
I then spent the next 4-5 hours dialing my primaries, secondaries, and tertiaries back down.
I stopped at 16-16-16-28 for the primaries. For completeness I should have attempted CL14, and may go back and do that. CL16 worked, and I just assumed that CL14 (same as I achieved at 3800) would be a bridge too far, so I didn't pursue it. I probably should.
Result: Here's my Zen timings for my 3800/14-15-15-28 profile that I had. Btw, I had intended to set those 15s to 14 and retest back when I was OCing my RAM and just never got back to doing it, and since the benefits to doing so I knew would be exceedingly modest, I just never got around to it.
Here's a representative AIDA64 memory/cache test result while running that 3800/14-15-15-28 profile.
Here's my Zen Timings for the 4266-16-16-16-28 profile I'm running on as I type this. And here's a representative AIDA64 memory/cache test result at that profile.
As you can see, the Read and Copy bandwidth at the 1:2 synched DDR4 4266/16-16-16-28 profile were improved by around 10.5% while the latency suffered by around 7%. The Write bandwidth improved by a more modest 4.4% or so.
Discussion II: The question is, am I being helped more by these bandwidth increases than I'm hurt by the latency increases? That is yet to be determined.
So far it appears my Time Spy CPU score may have gone up modestly, though it's small enough that further runs at both profiles will be needed to be sure.
The Blender 6-image full benchmark run appears to have taken almost exactly the same time (23 minutes 54 seconds) . I'm not sure I'm going to take 24 minutes each to run multiple runs at each profile to be sure, since I got previous runs at my 3800/14-15-15-28 profile that were nearly exactly the same, down to the second. Blender appears to be a wash.
Cinebench R23 may have improved very modestly, but I only did 2-3 runs of it and the differences were smaller than the run to run variance, so more testing would have to be done. Not much change is expected either way with this benchmark, which is known to run out of the cache for the most part so that RAM speed doesn't affect it that much.
I'm about to boot up Far Cry 5 and run its built-in benchmark several times at each profile and compare its results in terms of avg. and 1% low FPS and see how that goes.
I've got some other games with built-in benchmarks like Ashes of the Singularity, Civ 6, Metro Exodus, and probably some others. I'll give those a try.
I know that Battlefield 2042 is pretty CPU heavy and I've played it quite a bit in the last few days, but with no built-in benchmark I'm not sure how I would accurately measure performance under these two memory profiles to see what difference they make. That's a shame, because if there's a currently relevant game that would be most likely to show an improvement with one over the other, that's probably it.
Request for Suggestions: I need more ideas of things I can repeatably test that are known to be impacted by memory speed and latency in order to get more of an idea whether the advantages I've gained in bandwidth outweigh the disadvantages in latency. Since gaming has recently been more of a thing for me I'll entertain suggestions of games that have benchmarks, that also won't cost me money just to test them, to see how they do.
Caveat: I have not yet run nearly the level of stability testing on this 4266/16-16-16-28 profile that I did on my 3800/14-15-15-28 profile. The 3800MT/s profile was rock solid. I've only run fairly short duration tests with the 4266 profile, and so far it's been fine. I need to do more. I did run a 40-minute stint of TM5 with the extreme@anta777 profile with zero issues. When I was uncovering problems with my 3800 profile several months back they always turned up with that extreme profile in TM5 earlier than that.
Also, I should mention that my RAM is running at 1.5V, is a 4x8gb G.Skill Samsung B-die kit, and that it's water cooled so the temps never get out of the low 30s, and since it was chilly in my mancave last night in fact the temps never got out of the high 20s Celsius. Running 3800MT/s at 1.5V originally would heat up my RAM after a sufficiently long run and eventually hit 50+ C and start throwing errors. I pointed a fan at the RAM and held its temps in the low 40s and avoided the errors, then put an EK water block on the RAM and held the temps to 1-2C over my water temps, which are low 30s while stressing CPU and GPU. Running at 4266MT/s at 1.5V would presumably hit that 50+ C temp range and error out even more quickly without some form of active cooling. Now that my RAM is water cooled the RAM temperature simply isn't an issue at all, and I'm not going to remove my water block and reinstall the factory cooling fins on my DIMMs just to test this out. So with non-actively-cooled RAM your mileage may vary.
I will be posting this same post to the overclocking sub because it's one I've also been active in and it might be of interest to them.
edited to add: the CPU is a Ryzen 9 5900x, motherboard is Gigabyte x570 Aorus Master v1.2. The CPU is water cooled and pushed aggressively with PBO2 and Curve Optimizer (Cinebench R23 all-core scores in the 23300-23400 range).
So, I'm new to AMD, atm I'm running my 5600x at stock clock with my xpg d60 4133mhz at 3600mhz CL16 and FCLK at 1800... Is this the right thing to do?
Hey so im not the sharpest tool in the shed and need someone thats kinda big brain to explain to me in monkey or something on how infinity fabric works. I have the general concept of it and just a few questions to help me understand it better.
Question 1: is infinity fabric passive? Do i have to activate something for it or does it mean i can just slap in a fast speed ram and the cpu just works the same as overclocking to the same speed. Like what if i just put in a cl16 3600 dual ram stick set would that just work the same as overclocking to the clock speed of 16?
Question 2: if question 1 isn’t passive then whats the point in overclocking at that point? and if i dont overclock and have a really fast speed ram does that mean its just better with amd or something if that ram is as fast as overclocking.
Question 3: if none of my questions make sense can i get a better explanation on what it is lol