RAM fails as a pair, not individually - how to rule out Motherboard or CPU fault

[Zeto]

Hey all!
I would like some help with diagnosing a Memory issue that popped up for me very recently. After multiple BSODs and various program crashes that seemed to link back to faulty RAM, I ran memtest to find multiple failures in Tests 7 and 13, consistently throughout all passes.
After further investigation;

A2 B2 XMP Enabled - Fail
A2 B2 Stock - Pass
A2 Either Stick Single, XMP Enabled - Pass
B2 Either Stick Single, XMP Enabled - Pass
A1 B1 XMP Enabled - No Post (as expected on this Motherboard)
A1 B1 Stock - Pass

Since my Sticks only fail together, and not alone, I'm second guessing on what is actually causing this issue. My system has been running issue free for over a year now - these problems have only started popping up after I cleared my CMOS to fix an (I hope) unrelated issue (USB PD in S5 wouldn't turn off - this fixed itself after clearing the CMOS).

Attached is the log of the failing test.

Would really appreciate some insights on this issue, thanks in advance

Specs are in the log anyway I assume, but here:

Motherboard: ASRock x570 Steel Legend
CPU: AMD Ryzen 5 5600x (no Overclocking or Undervolting of any kind)
RAM: Corsair Vengeance RGB Pro 3600MHz cl18 2x16gb

[David (PassMark)]

Using two sticks will place the RAM into dual channel mode and change the access patterns. So different behaviour isn't all that unusual.

See also
https://www.memtest86.com/troublesho...htm#consistent

As changing the RAM is easy, try that first.

[Zeto]

I was hoping that it was maybe just a BIOS config issue or something easy to fix haha. Guess I'm RMAing this kit. I'll update the thread if the issue persists with new RAM. Thanks!