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ROG Crosshair VIII Hero / FORMULA / IMPACT / DARK HERO / EXTREME LN2 OC Guide


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On 11/15/2020 at 5:01 AM, flanker said:

Stay in BIOS to  -40C, set fclk between 1100-1600MHz (depends on chip), also u have VSOC set to 1.4-1.5V.  After u will have -40C, save+exit this needed values and go to Windows. And in Windows u can continue cool down the chip. 

Thanks my friend, I did it, but for some reason, not changed. 

I appreciate you reply. 

Best wishes 

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Terrible 0d post, even in stock, no matter to follow or no the excellent guide (very helpful). 

Tested several kits of RAM, 2 X 5950X and 1 X 5900X, and I can't even touch the memory timings. 

0d, 0d, 0d, etc. 

Temperatures, FCLK, SOC, etc, no matter the changes, not helps. 

3 BIOS different tested and nothing ?

 

That's a pity!!! 

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Today's ln2 experience on 2x Impact.

strated with bios 2502, ln2 switch on, -20C in bios, posting only possible after cmos reset, if i set anything manually, error code F9 and no post. I kept trying and struggling for like 30 minutes at least.
same behavior with 2402... so downgraded to 2311 where finally this issue disappeared. I was able to bench flawless after that. -142C boot at FCLK1900 no problem, CB -149.

Friend of mine was benching next to me with his same cpu+board setup, he kept trying with 2402 bios, got the very same issue. He figured out that ln2 jumper disabled is eliminating the not posting F9 issue under cold. He continued to bench with that bios and had a lot of struggle with coldbug at around -130 and coldboot at -100C.

We also experienced efficiency difference in R15 which i think might be related to the different agesa patch. Not sure, could be something OS related but after I examined the uploaded results, I see a slightly chance to bios 2311 scores are lower compared to same clocks on newer bios. Would need to rebench to figure out, but I'm out of ln2 and the will to refill. 

Good luck fellas, this will be a bumpy ride :D

Edited by Achill3uS
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Hello, feedback with my Ryzen 9 5950X on the Crosshair VIII Dark Hero (BIOS 2402).
Under watercooling 4.7 GHz 1.19v R15/R20 and 4.8 GHz 1.29v.

guide-overclocking-vermeer-5000-ryzen-cr

guide-overclocking-vermeer-5000-ryzen-cr

 

First test under LN2 with my Ryzen 5950X on the C8D. The CPU takes 5.8 GHz at 1.5875 volt (multimeter) at -155°C. I think I have a coldbug at -160°C and I also have a code 07 coming in while the FCLK frequency is only 1400 MHz. I will do another set of tests tomorrow.

5950x-cinebench-r15-ln2-5800mhz-overcloc

 

SOC : 1.35v - VDDG CCD : 1.15v - VDDG IOD : 0.9v - PLL : 2.1v
Do you think my coldbug at -160°C can come from the FCLK? If I put a voltage higher than 1.62v, the motherboard will reboot directly, so even at -155°C, I can't try to increase the frequency.

 

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Yes, FCLK 100%.  I had also seen a cpu that simply ran fullpot only for ...5 minutes or something like that then never again. Air is same but fullpot is simply not possible.  Anyways, thank you AMD for the I/O die being made on the cheap 14nm and creating these issues on cold.  

 

@rbuass When are you trying to apply timings and freq? Easiest way. Go -40 -50 , load ln2 profile, apply, keep the temp, then apply your ram timings and such, get things working then cool down. You might or may not experience restarts on the way to fullpot , this again depends on the chip itself, i had chips doing two restarts on the path to fullpot while i had a chips  that i accidentaly loaded ln2 profile , went into windows and cooled all the way from +25 to  fullpot and everything worked. 

 

To conclude, 5xxx series has same cold issues as 3xxx series except the fact that by results the 6 core and 8 core do higher flck while cold.  The 12 and 16 core is a gamble on cold again, some cpu's will simply not work fullpot no matter your ram speed  or infinity fabric clock or bios or board or whatever. 

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On 11/23/2020 at 12:22 AM, Alex@ro said:

"...I had also seen a cpu that simply ran fullpot only for ...5 minutes or something like that then never again.
...
i had chips doing two restarts on the path to fullpot..."

Haha this happened to me. It was 2nd session. FP 1900FCLK Gen3 PCIe.
IDK if it's can happen again randomly, or just never again.  But still, can't bench in this condition.

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used that BIOS first on my 5600x/impact combo.

it "worked"?

idk what issues you refer to but used it to install windows and ran some benchmarks etc.

now back on 2402 so i can get higher than 1900fclk so can't say anything about longer term sorry.

 

basically we are all beta testing this shit right now anyway.

or as AMD likes to put it "hardware aging like fine wine"

 

 

edit: 2402 has its own quirks though. often needs "retry boot" even on stock settings to turn on/restart.

and while i was able to hit max 2100mhz, anything over 1900fclk seems hit and miss, mostly miss. despite being stable in benchmarks its not any faster (possibly slightly slower even) and otherwise randomly very unstable - random restarts, slowness, laggy kb/mouse inputs. annoying.

probably a good reason its "locked out" for now..

Edited by t8y
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On 12/2/2020 at 3:59 AM, t8y said:

used that BIOS first on my 5600x/impact combo.

it "worked"?

idk what issues you refer to but used it to install windows and ran some benchmarks etc.

now back on 2402 so i can get higher than 1900fclk so can't say anything about longer term sorry.

 

basically we are all beta testing this shit right now anyway.

or as AMD likes to put it "hardware aging like fine wine"

 

edit: 2402 has its own quirks though. often needs "retry boot" even on stock settings to turn on/restart.

and while i was able to hit max 2100mhz, anything over 1900fclk seems hit and miss, mostly miss. despite being stable in benchmarks its not any faster (possibly slightly slower even) and otherwise randomly very unstable - random restarts, slowness, laggy kb/mouse inputs. annoying.

probably a good reason its "locked out" for now..

My experience with 2402:

- FCLK/UCLK worked 2000Mhz, superb performance! But only the first day. Second day, with the exact same settings, no go. Not even 1900 was stable the second day. And performance was like he CPU lost half cores :))). Tried 3 Windows, reset BIOS, etc. The only way to get the performance back was to flash another BIOS (2701)

 

With 2311 & 2701 performance is very good. No stability issues today, for 8 hours. Yet, no start with FCLK/UCLK above 1900MHz.

(C8H Wifi + 5900X + 2x 8GB GSkill Royal 3600C16)

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