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*Official* Intel DDR5 OC and 24/7 daily Memory Stability Thread

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#22,081 ·
UnderClockedOverVolted said:
At least you got C36 to work for 8200 @opt33 , I cannot for the life of my figure out why if I change 38 -> 36 it insta fails.

For example, my 38 passes every test under the sun but when I change CAS to 36 it fails. Not even just 1 error but many errors start popping off. I tried to supplement extra voltage - so I started with 0.05v addition which failed, so I added an entire 0.10v and that did the same thing.

Are there specific timings that need to be altered when reducing tCL? I know there are several functions involved with many DDR5 timings, where if you change 1 number you need to change another or multiple others. I always assumed CAS can simply be reduced, you just had to add some VDD/VDDQ.

And...

Another thing, in terms of setting functional trfc2 and trfcpb with 48GB kits, are specific number ranges or numbers that need to be used? Do they need to divide into specific steps that correlate with other timings? For exmaple, whatever you set trfc2, it needs to be divisable by 16 or 32, and same goes for trfcpb? Do other timings need to be divisable by certain numbers in order to work correctly? I just need more clarifications on the DDR5 rules - specifically ones paramount for 48GB modules. The only "rules" I found in a search were related to 16GB kits which don't translate 100% to 48GB kits.
Click to expand...
If you change CL by -2 from before, you must also change
tCWL by -2
tWRPRE by -2
tWRPDEN by -2
tRDPDEN by -2

Assuming WTRL/S is on AUTO:
tWRRDsg by -2
tWRRDdg by -2
 
#22,082 ·
J_Lab4645 said:
I went through several sets of TG dimms to try and get 8600 on air. Tried TG Xtreem (2x16) 7600,(fail) Tried TG RGB Delta (2x24) 8200,(fail) and the winner was TG Xtreem (2x24) 8000 like you have posted. Must have finally gotten a good bin, that + Bios 0801 made it easy peasy. Pretty nice for no water cooling. Still playing around w/tRFC/tRFCpb which need to be conservative for 8600 on air because of heat (still testing to see minimums but grateful for 30 day return policy for sticks that didn't work out! -Enjoy.
Click to expand...
looks like if you have a good imc does help to bin ram if on air. With my imc, not so much, all 3 48gb kits do 8200 easy and none 8400 for VST. 32gb kits more variable but higher bins limited 8000 on my imc.

Bumper Font Automotive design Electronic device Advertising
 
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#22,085 · (Edited)
So been testing minimum tRFC/tRFCpb @8600 on TG Xtreeem (2x24) 8000 and it has been a fine line between passing mem tests or not since we are not on water cooling. This has been the minimum I can pass. tRFC 878/tRFCpb 758. Maybe can go lower, Maybe not. but even though these dimms have a great aluminum heatsink, you've got to keep these pups below 40C. Respect to y'all with water cooled dimms. Now I get it.
IMC=1.425
TX=1.385
SA=(Auto)
Vdd/VddQ= 1.5
 

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#22,086 ·
opt33 said:
looks like if you have a good imc does help to bin ram if on air. With my imc, not so much, all 3 48gb kits do 8200 easy and none 8400 for VST. 32gb kits more variable but higher bins limited 8000 on my imc.

View attachment 2641111
Click to expand...
So full disclosure. When I have my ram Oc'd to 8600, I have my AVX down binned (2) from P57/E44 to P55/E44 to pass Y-cruncher/VST. I don't have direct die. These stress tests I will fail @ P57/E44. (I can't cool this). I do pass at AVX offset of 2. P55/E44.
 
#22,087 ·
CarSalesman said:
Lowering RFC/RFCpb forces the refresh command to finish more quickly.

Raising tREFI makes the refresh command happen less often.

Doing either or both will improve performance.

Being able to lower RFC/RFCpb is a question of silicon lottery with the available VDIMM voltage, while being able to raise REFI is dependent on your cooling for your RAM sticks.

EDIT: For RFC/RFCpb choose from:

448/364 <probably best case scenario for H16A @ ~8000
480/390
512/416
544/442
576/468
608/494 <probably best case scenario for H24M @ ~8000
640/520
672/546
704/572
736/598
768/624
Click to expand...

I got the tREFI at 65000 stable, is it worth lowering tRFC(2)/tRFCpb down to 448/364?
 
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#22,088 ·
TK421 said:
I got the tREFI at 65000 stable, is it worth lowering tRFC(2)/tRFCpb down to 448/364?
Click to expand...
Depends what your definition of worthiness is. You can just punch in the values and try. It will likely not post if you try too low tRFC/tRFCpb.
 
#22,089 ·
CarSalesman said:
Depends what your definition of worthiness is. You can just punch in the values and try. It will likely not post if you try too low tRFC/tRFCpb.
Click to expand...
Helps CPU-bound games


Also what timing do I tighten first if I manage to get find stable tRFC(2)/tRFCpb?

Font Screenshot Technology Electronic device Software








pipes said:
There is a new testmem version here: TestMem5 • Конференция Overclockers.ru

And here for download Release v2023.12.06.3 · CoolCmd/3aIIyckaJIkaTestMem5
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Can I still use the old configs (anta extreme/absolut, 1usmus, pcbdestoyer)?
 
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#22,090 ·
TK421 said:
Helps CPU-bound games


Also what timing do I tighten first if I manage to get find stable tRFC(2)/tRFCpb?

View attachment 2641135









Can I still use the old configs (anta extreme/absolut, 1usmus, pcbdestoyer)?
Click to expand...
tRFC/tRFCpb don’t dictate what other timings can be. Perhaps I don’t understand your question.
 
#22,091 ·
opt33 said:
looks like if you have a good imc does help to bin ram if on air. With my imc, not so much, all 3 48gb kits do 8200 easy and none 8400 for VST. 32gb kits more variable but higher bins limited 8000 on my imc.

View attachment 2641111
Click to expand...
I did not realize retail ram was so limiting lol. I’m gonna test my sticks 1 at a time. Maybe I can find (2) in my (4) sticks that can pass 8600 together. I can pass 8400/8533c36. But I don’t think my new ram is capable of real 8600 stability.

Hows the 2x16GB life? Is that easier than 2x24GB?
 
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#22,092 ·
I hate memory overclocking, error'd out about 15 seconds after this SS.
Font Technology Screenshot Space Software
 
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#22,093 ·
tps3443 said:
I did not realize retail ram was so limiting lol. I’m gonna test my sticks 1 at a time. Maybe I can find (2) in my (4) sticks that can pass 8600 together. I can pass 8400/8533c36. But I don’t think my new ram is capable of real 8600 stability.

Hows the 2x16GB life? Is that easier than 2x24GB?
Click to expand...
2x24 gb clock higher with my mediocre imc.
 
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#22,094 ·
CarSalesman said:
tRFC/tRFCpb don’t dictate what other timings can be. Perhaps I don’t understand your question.
Click to expand...
I mean, once I tune tRFC/tRFCpb and it's stable, what other timings should I try to tighten first?
 
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#22,095 ·
TK421 said:
I mean, once I tune tRFC/tRFCpb and it's stable, what other timings should I try to tighten first?
Click to expand...
Why don't you just trial and error, lowering trrds/trrdl/tfaw etc along with other terts and just working down as long as it is stable. People here can't spoon feed every timing/change to you 1 by 1. You need to experiment and see what is stable on your setup.
 
#22,096 ·
TK421 said:
I got the tREFI at 65000 stable, is it worth lowering tRFC(2)/tRFCpb down to 448/364?
Click to expand...
getting tRFC2 and tRFCpb too low can just cause instability or even a failure to train at all. Those timings mostly affect bandwidth. you just need to find a happy medium for the values to be at. For example at 8400 38-49-49-96 I've got tREFI set to 262143 and tRFC2 at 740 and tRFCpb at 680. For my setup keep these values slightly higher than the XMP Tweaked defaults has kept my overclock very stable. Some people with even better IMC and sticks can get away with lower. I'm also using DIMMFLEX in the Asus BIOS to reduce tREFI a step down at 42c to 131071 if it ever reaches that temp. While gaming my max DIMM temps are typically 38-39c depending on ambient temps at a tREFI of 262143(higher tREFI will make your DIMMs get warmer sooner).
 
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#22,097 ·
YaqY said:
Why don't you just trial and error, lowering trrds/trrdl/tfaw etc along with other terts and just working down as long as it is stable. People here can't spoon feed every timing/change to you 1 by 1. You need to experiment and see what is stable on your setup.
Click to expand...
found conflicting info on which to start first, github guide says main timings first but you say the secondaries first



UTVOL06 said:
getting tRFC2 and tRFCpb too low can just cause instability or even a failure to train at all. Those timings mostly affect bandwidth. you just need to find a happy medium for the values to be at. For example at 8400 38-49-49-96 I've got tREFI set to 262143 and tRFC2 at 740 and tRFCpb at 680. For my setup keep these values slightly higher than the XMP Tweaked defaults has kept my overclock very stable. Some people with even better IMC and sticks can get away with lower. I'm also using DIMMFLEX in the Asus BIOS to reduce tREFI a step down at 42c to 131071 if it ever reaches that temp. While gaming my max DIMM temps are typically 38-39c depending on ambient temps at a tREFI of 262143(higher tREFI will make your DIMMs get warmer sooner).
Click to expand...
is the dimmflex feature exclusive to apex? I don't see it on the hero
 
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#22,100 ·
UTVOL06 said:
getting tRFC2 and tRFCpb too low can just cause instability or even a failure to train at all. Those timings mostly affect bandwidth. you just need to find a happy medium for the values to be at. For example at 8400 38-49-49-96 I've got tREFI set to 262143 and tRFC2 at 740 and tRFCpb at 680. For my setup keep these values slightly higher than the XMP Tweaked defaults has kept my overclock very stable. Some people with even better IMC and sticks can get away with lower. I'm also using DIMMFLEX in the Asus BIOS to reduce tREFI a step down at 42c to 131071 if it ever reaches that temp. While gaming my max DIMM temps are typically 38-39c depending on ambient temps at a tREFI of 262143(higher tREFI will make your DIMMs get warmer sooner).
Click to expand...
Is dimmflex a Apex feature? Maybe called something else on MSI boards? This would be amazing to have. I run 65535 due to temps, at 65535 I don't error when my RAM ICs hit 50c. It would be nice to be able to down clock once it hits 45c.

Time to do some googling.
 
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