Crosshair X870E Hero EXPO problem

[In_Flames]

Hello,

I have a Crosshair X870E Hero and Ryzen 9 9950X3D.
BIOS ver. 1512 (2025/06/13)

I bought 2 of G.SKILL 32 (2X16) Trident Z5 Neo RGB 8000Mhz EXPO memory kits for this system, a total of 64 GB. The full product code is; F5-8000J3848H16GX2-TZ5NR.

The problem I am experiencing is that when I select any of the EXPO, EXPOII, EXPO Tweaked, EXPO on the fly options, it does not boot. When I select manual, it does not boot at 8000Mhz. When I proceed by selecting backward frequencies in the manual option, it boots at 7200Mhz. However, with this option, most of the games I play constantly crash. When I put it back to default, there is no crash in the games, but this time the RAM is working at 3600Mhz.

I don't know much about the subject, what should I do to get both stable work and maximum efficiency?

[Brainbl33d]

8000 Mhz is way too high for 9950x3d.  Get yourself a 6000 Mhz kit and your system will have no issues.

[Nate152 · Accepted solution]

Hello In_Flames

You're having issues because you're combining two memory kits.

Shut down your pc and unplug the power supply cable.

Install one memory kit in slots A2-B2 (2nd & 4th slots from the cpu).

Press and hold the clear cmos button for 3 seconds.

Boot up your pc and try EXPO.

From G.Skill:

[In_Flames]

Hello, I tried as you said and it works fine. But it was a pity that one of the kits was trash. 😔

[Nate152]

It may not necessarily be trash.

When you combine 2 memory kits, you're doubling up on the capacity at the same frequency. It's too much for the cpu's memory controller to handle.

You may get all 4 sticks to work, but you'll have to settle for a much lower frequency. 

[In_Flames]

Thank you very much for your help. It works very stably on 3600Mhz as 4 slot. I will try to find the highest frequency that will work stable by increasing the frequency step by step.