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Rog Crosshair Hero X670E with 7950X3D Not Posting with Expo Enabled (GSkill z5 128 GB)

Level 8

Hi Everyone,

when i enable EXPO-1 or Expo-2 or even Expo-Tweaked in the bios my system refuses to boot and it will always go into safe mode. When i load optimized defaults the PC will boot and work properly with DDR-5 frequency as 3600 MHz. I have tried incrementally increasing the memory clock frequency and the maximum stable frequency i am getting is 4000 MHz. Once i go past 4000 MHz the bios is not POSTING and i am getting "C5" error. Only way currently recover from "C5" error is to remove 3 RAM sticks and boot with only one.


Did anyone got the AMD expo working with Crosshair Hero X670E with fill 4 DIMMS?
Did anyone tried with the latest 1516 BETA Bios?

Below is my system configuration :-

Processor:- AMD Ryzen 7950X3d
Motherboard:- Rog Crosshair Hero X670E  

Memory:- GSkill Trident Z5 6000MHz (30-40-40-96)
GPU:- Rog Strix 4090 OC @ 24 GB

Chassis:- ROG Hyperion GR701

Power Supply:- Rog Thor 1200W P2
CPU Cooler:- Rog Ryujin III 360

Customer Service Agent

Hello, @avinashga23 

May I ask which version of BIOS you are currently on?
We recommend updating to beta BIOS 1516, performing a clear CMOS, and verifying that the system can boot successfully before attempting to enable EXPO or any related manual settings.

Additionally, may I inquire if you are currently using the memory part number F5-6000J3040G32GX2-TZ5NR, which consists of 2x32GB modules?
We recommend using memory modules from the QVL and installing them in the slots recommended in the user manual.

Thank you.


I can confirm that the memory modules i am using is GSkill Z5 neo F5-6000J3040G32GX2-TZ5NR. I am using 4 ram modules of 32 GB each starting from serial number 65,66,67 and 68. I have also placed the 65 in the first slot and 66 in the third slot, also i have placed 67 in the second slot and 68 in the fourth slot.

I will try updating the bios to latest 1516 beta version over weekend and check.

Level 8

I have upgraded to the latest 1516 BETA bios and can confirm that the maximum memory speed i am getting stable is 4000 MHz. Anything past 4200 MHz is not stable but it will POST. Anything beyond 4200 MHz wont even post and result in either safe mode or C5 error.

I also tried with Expo-1 Expo-2 and even Expo-Tweaked and none works

Customer Service Agent

Hello, @avinashga23 

After verification, it appears that the ROG CROSSHAIR X670E HERO only supports the 2-module kit with the part number F5-6000J3040G32GX2-TZ5NR.

We recommend that you first install a single memory module within the QVL in the recommended slot and check if you can enable EXPO I.
If EXPO I can be enabled successfully, then proceed to install the two memory modules in the specified slots and confirm the functionality. 

Thank you.