3800x + Corsair 32GB Kit Latency?

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supra21

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I have a Gigabyte Aorus Master x570 (F34 Bios), 3800x in PBO mode and 32GB of Corsair CMT32GX4M4C3200C16 (4x8gb) ram.
I only use this pc for gaming at 1440p@120hz / 4K@60hz, so did not see the benefit in going to 3600mhz with looser timings.

I have been tightening the timing of the ram at 3200mhz to as low as they can go in order to reduce latency. This is the best I've gotten them to:
Zen-Timings-Screenshot.png
With the XMP profile running the latency test in AIDA64 a few times lowest I get is 76.4ns. With the timings above its around: 73.7ns. Is there anything else I can do to get the latency lower or is this normal / expected?
 
I would try loosen timings and see what frequency you can get it up to as it may do 3600+ just fine depending on what chips it has.
 
tRFC can come down. Probably a lot. tRTP also looks too high, especially since you tightened tRAS so much. Half of tWR is the rule of thumb for that one. You can try 4/6/24 or possibly 4/6/16 for tRRDS/tRRDL/tFAW. Good kits can do 4/4/16 easily at 3200/1.35V, but yours is C16-rated, so who knows.

Your tRC value is invalid. It can't be less than tRP+tRAS.

Anything else will probably need more vDIMM.
 
Last edited:
JSHamlet234 said:
tRFC can come down. Probably a lot. tRTP also looks too high, especially since you tightened tRAS so much. Half of tWR is the rule of thumb for that one. You can try 4/6/24 or possibly 4/6/16 for tRRDS/tRRDL/tFAW. Good kits can do 4/4/16 easily at 3200/1.35V, but yours is C16-rated, so who knows.

Your tRC value is invalid. It can't be less than tRP+tRAS.

Anything else will probably need more vDIMM.
Click to expand...

Thanks for the tips, I managed to tighten the timings more with your advice but latency result is still 73.7ns. For some reason even though I set tRTP to 7 it just sets it to 8, no idea why. I think I can set it to 6 and that sticks.
If I lower the tRFC any lower than 408 I get BSOD.
ZenTimings_Screenshot new.png
 
Try upping your voltages you are leaving alot on the table with tRFC @ 408

Set
SOC = 1.050
VDDP = .950
VDDG = .950
VTT = .950
VDIMM 1.375

All of those voltages are 100% safe. See if that will let you reduce your tRFC at all
 
tRFC 408 is very low for almost anything that is not samsung b die.
 
dasa said:
tRFC 408 is very low for almost anything that is not samsung b die.
Click to expand...
According to everything that I am reading online if these are the 8gb modules in a 32gb 4 stick configuration as advertised these are Samsung B Die... The only true way to tell is fire up Thaiphoon Burner and see.... The OP left this detail out of the main post. If they are in fact B Die as they seem to be then a 408 tRFC does in fact leave alot on the table. Most B Die is good down to tRFC 250-300
 
Enigma said:
According to everything that I am reading online if these are the 8gb modules in a 32gb 4 stick configuration as advertised these are Samsung B Die... The only true way to tell is fire up Thaiphoon Burner and see.... The OP left this detail out of the main post. If they are in fact B Die as they seem to be then a 408 tRFC does in fact leave alot on the table. Most B Die is good down to tRFC 250-300
Click to expand...
Unfortunately it's not Samsung B Die, I believe they are Hynix CJR:
Screenshot 2021-10-03 133023.jpg


Also 408 was too tight, got crashes in gaming after a few hours, 410 seems to be the limit at stock voltage settings.
 
tRFC probably wont scale with increase V if it is CJR.

A few things you could try.

tCWL 12.

tRTP 6, tWR 12, tRDWR Auto.

Lower tRAS as far below the rule as you need to get tRC as low as you can while stable.

Lower ProcODT.

GDM disabled 2T or 1T (1T may require AddrCmdSetup56 to post)

Test for stability with TM5 at current settings and between each step above.
 
I stand corrected, tRFC infact will not scale with voltage on CJR ram.... Below is what Dram Calculator suggests, While only a guide it is showing with some voltage tweaking you should be able to get things pulled just a little bit tighter like dasa said, Lower the ODT and tweak the RTT settings that should bring latency down just a hair. There will be some gains to be had increasing the SOC,CCD,IOD,and VDDP voltages slightly.

HynxCJR.png
 
Sometimes AMD systems won't take odd digit timings for some reason. My original kit was 3600/CL19 in 2019 but it would only post at CL20. Ended up sending it back for some CL16 and that's what it runs at with no issue.
 
kent said:
Sometimes AMD systems won't take odd digit timings for some reason. My original kit was 3600/CL19 in 2019 but it would only post at CL20. Ended up sending it back for some CL16 and that's what it runs at with no issue.
Click to expand...

Typically this is caused by Geardown being Enabled/Disabled. As far as the others being odd or even it will not cause any problems.
 
dasa said:
tRFC probably wont scale with increase V if it is CJR.

A few things you could try.

tCWL 12.

tRTP 6, tWR 12, tRDWR Auto.

Lower tRAS as far below the rule as you need to get tRC as low as you can while stable.

Lower ProcODT.

GDM disabled 2T or 1T (1T may require AddrCmdSetup56 to post)

Test for stability with TM5 at current settings and between each step above.
Click to expand...

Based on your recommendations this is what I was able to achieve:
ZenTimings_Screenshotsmall.png

I was unable to disable geardown mode, using 2T or 1T with AddrCmdSetup 56 I get BSOD at desktop. Still after running latency test lowest result I get is 73.7ns
 
supra21 said:
Still after running latency test lowest result I get is 73.7ns
Click to expand...
For a 3700X at 3200 that is probably not to bad.
If you could get it to run 3600-3733 and launch windows in diagnostic mode to run the latency test you may get under 70ns

If you wish to try for 3600+ set all the timings to auto and see how high it will go with up to ~1.45VDIMM but you may find it gets less table over ~1.38VDIMM it just depends on the chips.
Also these settings may help stability a bit.
RttNom RZQ/6
RttWr RZQ 3
RttPark RZQ/3

For higher frequency you will likely also need up to 1.2V VSOC & 1.1V VDDG IOD.

One you find the max stable frequency start tweaking the timings down again.
 
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dasa said:
For a 3700X at 3200 that is probably not to bad.
If you could get it to run 3600-3733 and launch windows in diagnostic mode to run the latency test you may get under 70ns

If you wish to try for 3600+ set all the timings to auto and see how high it will go with up to ~1.45VDIMM but you may find it gets less table over ~1.38VDIMM it just depends on the chips.
Also these settings may help stability a bit.
RttNom RZQ/6
RttWr RZQ 3
RttPark RZQ/3

For higher frequency you will likely also need up to 1.2V VSOC & 1.1V VDDG IOD.

One you find the max stable frequency start tweaking the timings down again.
Click to expand...
Ok after painful amount of boot failures and my mobo not being able to see my boot drive unless I turned the psu off and back on again I found anything above 3600 is not bootable. I then resorted to the ryzen dram calculator to get some safe timings for 3600. With these timings I get a latency result of 68.9ns, so progress:
3600s.png
 
Almost 5ns lower nice progress.

Try
4 tRDS 6 tRDL 16 tFAW
tRTP 8 tWR 16 or 10\20

SCL 4.

tRAS 36 tRC 60
 
I could tighten a bit further in some areas, but I don't think it would make much difference:
Screenshot 2022-01-29 122038.jpg
 
tFAW 16 should have improved bandwidth a bit.

tWR should be double tRTP or you may lose some performance.
So if you can run tRTP 5 then tWR 10 is ok but otherwise I would increase it.

SCL 4 no go?
 
dasa said:
tFAW 16 should have improved bandwidth a bit.

tWR should be double tRTP or you may lose some performance.
So if you can run tRTP 5 then tWR 10 is ok but otherwise I would increase it.

SCL 4 no go?
Click to expand...
Ok made those changes and SCL to 4 and all is stable. Did not make a difference to latency result but overall still a nice improvement.
 
Congrats on squeezing a nice bit of extra performance out of the old CPU\RAM.
 
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