Jump to content
HWBOT Community Forums
safedisk

ROG Crosshair VIII LN2 OC Guide

Recommended Posts

Posted (edited)

LN2 BIOS 

ROG CROSSHAIR VIII FORMULA / HERO 0042 BIOS

FORMULA : https://bit.ly/32fMVrz

HERO https://bit.ly/2NGkM9X

 

ROG CROSSHAIR VIII FORMULA / HERO 0090 BIOS (but LN2 cbb)

FORMULA : https://bit.ly/2LI2cf6

HERO https://bit.ly/2JlUMMO

 

OCPACK

Download : https://bit.ly/2XyAtVt


USB Flashback

1559113709797.thumb.jpg.30a6cec7ea4021d1ed5e181b19044e2c.jpg

 

 

LN2 OC TIP

There is an FCLK cold bug under LN2 so try to stay around 1400~1600 for FCLK under LN2 to get a good compromise between temps and perf.

To improve stability in this case:

VDDG 1.15v, SOC 1.28v, disable DF Cstates.

Depending on the CPU and FCLK, may have to control temps -120C ~ -170C.

 

Do not be alarmed when it resets when temperature changes, pcie and fclk needs to retrain when temps change. Also sometimes there is temperature hole so going lower than it hangs may help.

 

FCLK
Biggest problem on the platform

1200 default freq and supposed to go 1:1 with memory for best latency.
Improves performance but limited, ~ 1800+ on air and 1400 on LN2.
FCLK instability includes hang at postcodes such as ‘07’, stuttering in OS, drop performance in Cinebench.
CPU has FCLK cold bug.
Improve FCLK Margin by using 1.15VDDG (too much will hang) and 1.3+v SOC. Since VDDG is sourced from SOC so SOC should be higher. VDDG only takes effect at 1400+ FCLK so under LN2 you need to set 1400. Higher usually fails during LN2.

Enable LN2 mode, Use the Load LN2 profile as a base template, this uses low vcore so you can save exit when it’s not cold. You will need to do this before -40C to avoid cold bug. You need 1400 FCLK + 1.15v VDDG and 1.35~1.45VSOC.

 

About AMD Limitations

Safemode cannot restore back to stock memory settings as this takes place in the ‘PSP’ which the BIOS has no control over at that point of time. Either you have to clear cmos or wait for 5 times of post code ‘F9’ to get into AMD’s recovery mode. AMD’s recovery mode restores every AMD option back to stock, including timings and CLDO voltages.

Because of the above, try not to clear cmos during LN2, at most go safe mode if your settings can be sustained with 1.5v DRAM, since BIOS will apply 1.5v for safemode when LN2 enable. IF you clear cmos, FCLK will go back to Auto and CLDO VDDG voltage will too. When cold, FCLK needs to be 1400+ and VDDG 1.15v if not Fabric will be unstable so you need to torch up to maybe -60c in this case. Therefore test your Memory settings on ambient first. Cold CPU improves Memory OC so you don’t need to worry about MC cold bug.

TRY NOT TO CLEAR CMOS WHEN CPU IS COLD

 

1559216408982.jpg.adcdb71ef7bb662f14bcdb54c2f39cec.jpg

 

1559216734738.jpg.9ad5e7dab8aedbdc0407930067dbf42a.jpg

 

Enjoy!

Edited by safedisk
  • Thanks 6

Share this post


Link to post
Share on other sites

good guide, u can update it also with your results+photos, it is welcome :) I have FB, but not all of us have FB :)

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...