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Ryzen 3000 RAM @ CL15

loafbred

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I haven't seen but one or two mentions, anywhere, of running RAM at CL15 since the Ryzen 3000's were released, so I thought it might be worthwhile to make a thread where we can record our succeses and failures with various dimms and chipsets. My hardware info can be seen in the two links below.

After running for a couple of days with latest BIOS and drivers (as of 8/5/19), I decided to play with RAM timings again at 3600 MHz. I've been running my 2x8gb G.Skill 2933 Flare-X CL14 at 3600 MHz, 16-17-16-36-1T with 1.35v, which has been ultra-stable. Today I tried 15-15-15-30-1T (other timings are fast) with 1.42v, and ran prime95 blend for a while without issue. I'll try reducing voltage to 1.40v tomorrow, and let that run for a couple of days before reducing it more. The only benchmark I have to compare to CL16, as of right now, is geekbench 4:
3600 MHz CL16

3600 MHz CL15
 
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loafbred

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I spent a few more hours playing with sub-timings and ended up with the settings in the image below. It failed Memtest at 1.41vdimm, still good after a couple of hours at 1.44v. I'm also linking the last Geekbench result.

DON'T FORGET TO TURN OFF "GEARDOWN MODE" when using CAS 15.

The latency settings located to the right of the originals are the ones I'm using. The two "_SCL" settings, which are changed to "2", required extra voltage, but made a noticeable difference.
DramCalc3600cl15.jpg
Edit: I failed to add the actual tRAS value, is now correct.
DramCalc3600cl15.jpg
New Geekbench result
 
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lopri

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Geardown mode helps stability at the cost of some performance. As with everything memory-related, it is a give-and-take. You give up some timings for higher frequency, and vice versa. Considering the impact of fclk (Infinity Fabric frequency) on Matisse platform, I think the best way to go about it is to raise the frequency on 1:1 basis as high as you can then to tighten timings (including on/off-ing Geardown mode)

Of course it appears you are already at near-limit of the platform (DDR4-3600), so disabling Geardown mode makes sense, as long as it is stable. I have had trouble maintaining stability with Geardown mode disabled past 3200 mclk.

tRDRD_SCL and tWRWR_SCL the tightest I have had is 3. I will try 2 and see what happens. Thanks for the tip!
 

loafbred

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Thanks for the info about Geardown, I haven't bothered looking into it yet. I may try higher frequency again later, but I read this week that the 3600s don't handle frequencies above 3600 MHz very well. I tried 3400 MHz CL14, but it didn't perform as well as what I have now. I didn't try 3600 MHz CL14, since I see recommendations of even higher voltage requirements.

As for the two "_SCL" settings, I was stable at 1.42v with those set at "4". I set them to "3", and lost stability. I went straight to "2" values and 1.44v, and all is still well. HWiNFO64 shows my dimm temp at 36* C with Valley benchmark looping, so I'm hoping I would be safe at 1.45v if needed. I'll check dimm temps today with Prime95 blend running.

Edit: Dimm temps never exceeded 41*, VRMs touched 50*. Dimm voltage often dropped to 1.428v, and occasionally to 1.416, max 1.52. It also dropped to 1.428v occasionally while idle.
 
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Adul

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I got my RAM at 16-16-16-38 at 1.36 v with a 1800 IF. I havent pushed harder but things seem to be stable for the past few weeks so time to push on.
 

IEC

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Using 1usmus' Ryzen DRAM calculator v1.6.0.3, Samsung B-die single rank x4, v2 profile - 3600 FAST timings/subtimings, then applying 1866 MEMCLK and 1866 FCLK without changing timings:

3900X 3733 CL16 IF1867 Tuned v2.PNG

Very decent results for 4x8GB
 

Andrei.

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Jan 26, 2015
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The frequency advantage GDM will bring you will vastly outweigh the small timing difference of running CL15 over CL16. The performance hit of GDM is about 1.3% over running 1T, while enabling you significantly higher clocks.
 
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IEC

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I don't understand what that means. Can you elaborate a little?
GDM is sort of like running 1.5T. Small penalty over running 1T with GDM disabled. But enabling it may allow you to push beyond 3600, and perhaps significantly so to like 3800. If you can do that you end up gaining more performance via frequency gains despite the relaxed latency.
 
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loafbred

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Thanks for taking the time to explain that, I hadn't seen anything about it before. I'll give 3733 a serious attempt in the next couple of days.
 

IEC

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Thanks for taking the time to explain that, I hadn't seen anything about it before. I'll give 3733 a serious attempt in the next couple of days.
I should note that you'll probably need active cooling on your memory in order to handle the voltage required to go above 3600. I was getting the occasional error after several hours of memtest and I was wondering why, and then realized it was temperature-related...
 

lopri

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Using 1usmus' Ryzen DRAM calculator v1.6.0.3, Samsung B-die single rank x4, v2 profile - 3600 FAST timings/subtimings, then applying 1866 MEMCLK and 1866 FCLK without changing timings:

View attachment 9367

Very decent results for 4x8GB
It's not just a decent result but it's almost a max performance, isn't it? Even with just 2 DIMMs it is difficult to go beyond DDR3-3800 anyway. I am really confused as to which is the bottleneck on Matisse platform, the memory controller or Infinity Fabric. Practically they are one and the same until 1800-ish MHz. From there up the IMC runs at half the speed of IF, which makes me think it is the IMC that is the weakest link. But then again the IMC seems to handle memory a lot better than previous Zen, as you have shown us here with 4 DIMMs running at DDR4-3733.

What was the average clocking potential of Infinity Fabric for Zen/Zen+ CPUs?
 

IEC

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It's not just a decent result but it's almost a max performance, isn't it? Even with just 2 DIMMs it is difficult to go beyond DDR3-3800 anyway. I am really confused as to which is the bottleneck on Matisse platform, the memory controller or Infinity Fabric. Practically they are one and the same until 1800-ish MHz. From there up the IMC runs at half the speed of IF, which makes me think it is the IMC that is the weakest link. But then again the IMC seems to handle memory a lot better than previous Zen, as you have shown us here with 4 DIMMs running at DDR4-3733.

What was the average clocking potential of Infinity Fabric for Zen/Zen+ CPUs?
I think 1866 FCLK is pretty much the ragged edge of stability, at least my sample. Who knows if we'll see this improve with a maturing process or not.

I've seen some lucky samples hit 1900 FCLK with tuned timings, but like others have indicated it seems like additional strain on the IMC can actually reduce performance. So realistically, 3600 CL14 (2 DIMMs) or 3600 CL16 (with 4 DIMMs) seems to be the easy/easier target to hit.
 

lopri

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For me once testing is done I plan to settle at 3600/CL16 or 3733/CL16 due to questionable performance gain of CL14 at those frequencies. Plus, it takes something like 1.45V for the latter and the memory temp rises above 60C which makes me uneasy. 3600/CL16 seems stable around 1.35~1.36V with my setup, and temp remains below 50C at max usage. And of course as you mentioned we have this to contend with:



Uncore's power budget is reduced by whopping 30% by the time the cores are fully loaded.

Edit: My 3700X does (a pseudo) 1900 fclk (1867 mclk + 102 bclk) Lucky? Ha.

cachemem_b102_3800CL16_633b.png
 
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lopri

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The frequency advantage GDM will bring you will vastly outweigh the small timing difference of running CL15 over CL16. The performance hit of GDM is about 1.3% over running 1T, while enabling you significantly higher clocks.
I get the gist but the phrasing is ambiguous. Do you mean that performance loss by enabling Geardown mode is 1.3% of performance loss by running 2T over 1T at the same frequency?
 

ehume

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For me once testing is done I plan to settle at 3600/CL16 or 3733/CL16 due to questionable performance gain of CL14 at those frequencies. Plus, it takes something like 1.45V for the latter . . .
Can't disagree with you on final settings for your memory, but this DDR4 stuff seems pretty wimpy if 1.45v is a lot of voltage. I have a pair of DDR3 2000 RAMsticks in the basement. They are pretty old, now, but they were intended to run at 1.6v, and they had headroom. Some oldtimers can tell you about RAM that was intended to run higher still.
 

IEC

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I have active cooling on my RAM so I don't think my setup really qualifies as "normal" (lol). I'm more than happy to throw 1.45V at my DDR4 DIMMs all day every day as a result.

That said, as others have pointed out, the gains after 3600 CL16 are extremely marginal. So unless you enjoy tinkering, it's more headache than it's worth for most users. Though 1usmus' calculator takes most of the guess work out of trying to shave off a few ns here and there, and I expect it to improve further with future revisions.

I do need to do a comparison between SR B-die in a 2 DIMM configuration versus SR B-die in a 4 DIMM (2 DPC) configuration vs Micron E-die in a 2 DIMM vs 4 DIMM configuration at some point, but a lack of free time is the enemy.
 
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Hans Gruber

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I have some Bdie Sammy sticks. I was wondering how people were getting 14-14-14 timings. Then I realized they were going 1.4v+. I am 14-15-15 3200mhz with 1.35v on my test Ryzen rig. It's only an 8GB kit with a Ryzen 1200 CPU.

If Ram hasn't changed much over the years. The 1st setting is the most important. CL 14 is what you want. Then after that the timings are not as important unless you go very loose. A 14-14-14 is obviously ideal with DDR4.
 

lopri

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Can't disagree with you on final settings for your memory, but this DDR4 stuff seems pretty wimpy if 1.45v is a lot of voltage. I have a pair of DDR3 2000 RAMsticks in the basement. They are pretty old, now, but they were intended to run at 1.6v, and they had headroom. Some oldtimers can tell you about RAM that was intended to run higher still.
Does Winbond BH-5 ring a bell on you? I tried up to 3.3V in the quest of CAS 1.5.
 
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loafbred

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Shortly after my last posting, I experienced failure to enter forced sleep mode, followed by a blue screen. I tested 3800 MHz CL16 with the DRAM calculator settings (GDM on), which was stable, but performance dropped a little. I went back to 3600 CL15 with the settings in the attached image, using 1.44v, and it has worked well since.
DramCalc3600cl15B.jpgDramCalc3600cl15B.jpgDramCalc3600cl15B.jpg
 
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