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Asus ROG STRIX X670E-E problem with POSTing using Expo

AG1
Level 8

Hello ROG community, 
I think I found a weird behavoiur of my X670E-E Mainboard.
I just bought a new system with the following components:

  • Ryzen 7950x
  • X670E-E Gaming Wifi
  • LC II 360 cooling
  • Asus TUF RX 7900 XTX OC
  • 6000MHz (2x 16GB Kit) G.Skill Trident Z5 NEO RGB 
  • 2000GB Kingston FURY Renegade
  • Corsair 5000X RGB
  • Corsair RMx SHIFT Series RM1000x 1000W

Newest BIOS 1602 ist flashed.

From the beginning I had the problem that in 1-2 out of 10 reboots or cold starts, my comoputer won't POST. Mostly I received Q code 46, sometimes 0d or 00.
If POST was successfull, system was always stable while running. It also passed various stress tests.

I never had POST problems with the EXPO profile I or II deactivated. Only with the EXPO profile activated.

I contacted the support of my OEM and Asus as well as AMD.
I finally found out, that the key was to change 1 voltage setting.

My RAM runs at VDD and VDDQ voltage of 1.35v.
In the bios I saw that my CPU VDDIO / MC voltage remained at around 1.13v even with EXPO profiles activated. The setting was "Auto".

In the web I read that the VDDIO / MC voltage must be increased by the mainboard while using EXPO profile. This does not happen in my case automatically.

So I manually set the VDDIO / MC voltage for the CPUs memory controller in the BIOS to 1.2v. No other voltages were changed. And since then: No instabilities, no POST problems at all.

This is good news, but there are two reasons why I am posting this:

  • For others who have the same problem to maybe find an easy solution for POST problems with identical hardware
  • To receive opinions from the community regarding:
    Is it a BIOS version bug or a normal behaviour of the board? Might it be a hardware defect that my systems needs more voltage for the memory controller than my mainboard assumes under "Auto" settings?
    Is 1.2v for VDDIO dangerous in any way or ok?

Thanks a lot for your help in advance..

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10 REPLIES 10

Tuning for CPU signal variance when it pertains to memory overclocking comes down to alignment and using more voltage is not always the answer.

13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090