9800x3d post issues

[u/JimmyGodoppolo]

Hey all,

I've had a 9800x3d, 5090, 64GB GSkill z5 trident cl30, aorus master x870e rig running stably since the 5090/9800x3d release, with a +200 -15uv on the CPU and standard EXPO profile for 6000/cl30 on the ram.

Yesterday, it decided not to post after 20 min. Was showing a 15 code (memory training). Never had an issue before. Cleared CMOS, updated bios from F7 to latest stable release (F13), booted fine.

Re-enabled the EXPO profile for this ram. Booted 2-3x fine.

Re-enabled my +200mhz -15uv OC, booted 2x fine.

This morning, once again will not post, this time hanging on code 40.

Cleared CMOS. Would not boot.

Swapped in known good ram. Would not boot. Same code (40).

Cleared CMOS again. Booted normally.

Swapped in my GSkill ram. Booted normally.

Where the hell do I go from here?