Question Motherboard frying RAM?

[exm]

Hi all,
Let me start off with stating that I have been building PC since the early 90s. I'm a hobbyist who has done this before and has troubleshoot many issues. But this one is strange.
Here's the situation: up until a week ago I had a perfectly working build (build app 3 months ago):

• New case, New Seasonic 750W PSU
• Asus Z790 Prime motherboard
• Intel i9-12900K CPU
• G.Skill 2x16 DDR5 Memory
• 1 Tb NVME
• A770 16Gb GPU

Everything was working fine, no issues, no complaint.
However...
I decided to sell my Intel GPU since I don't game a lot, and I figured I might as well wait for Battlemage. So I shutdown Windows, turned the PSU power switch to off, unplugged from power, unplugged all other cables and remove the A770. I never disabled the internal CPU GPU. Pretty straight-forward, right?
However, after turning my computer back on (HDMI cable in the mobo HDMI-out), the computer turns on, no picture. Strange. So I tried all the troubleshooting you can think of:

• Second monitor. Monitor on/off
• Plug the A770 back in, see if that one works
• CMOS reset, removing CMOS battery to do a BIOS reset

Nothing worked. So out of desperation, I figured, the mobo is somehow fried. So I bought the ASROCK Z790 Riptide Wifi (better specs anyway). Re-installed everything, same problem. Okay, so next: stop to Microcenter. The helpdesk wasn't really helpful but at least the tried to boot the computer, same problem. So I walked out with a new i9-12900K and a new set of DDR5 memory to troubleshoot (15 days returns, I spoke with the guys there and they were cool with it).
I booted my computer with the new ASROCK motherboard, and the new memory and voila, the computer turned on! Hurray, bad memory! But wait, I'm not done.
So I figured to see what happened with the old ASUS motherboard:

• Reinstalled the old motherboard, with the new memory. Same issue again. No picture. Oh man, motherboard+memory issue?

Here comes the kicker:

• When I re-installed the ASROCK motherboard with the new memory (the setup that just worked), it's not working now. NO PICTURE!
• So I figured to swap the Intel CPU for the NIB I have here. NO PICTURE.

My theory, the only working theory I can think of, is that the Asus motherboard somehow fries the memory. I have another pair of memory ordered (this time from Amazon) to try out this theory. Does this makes sense at all? Any other thoughts (I was thinking PSU, but it's a brand new Seasonic PSU that's working fine and everything seems to be powering on)?
Glad to hear your thoughts.
(and yes, I tried dual channel and single channel memory configurations above)

 

[Ralston18]

This motherboard?

https://dlcdnets.asus.com/pub/ASUS/...26_PRIME_Z790-P_UM_WEB.pdf?model=PRIME Z790-P

 

[exm]

This motherboard?

https://dlcdnets.asus.com/pub/ASUS/mb/LGA1700/PRIME_Z790-P/E20426_PRIME_Z790-P_UM_WEB.pdf?model=PRIME Z790-P

Yes. The “WiFi” variant of the “p”.