Question Swapped only CPU but can't boot anymore

[TemporarySoil]

Hello,

I changed my build's CPU, and only the CPU but now my PC won't post anymore.
I have debug LEDs on my motherboard. At first they go red->orange->red->stays orange for more than 30 minutes.
I initially thought it was going through memory training, but it shouldn't take that long. My CPU is intel.

This build booted perfectly before, so I don't understand why I get a RAM error when I didn't even touch it. I simply swapped the CPU and touched nothing else.
I did clear CMOS and now same thing happens but the PC shut downs after a couple minutes.

I have checked that this CPU is compatible with the motherboard, also I updated to the latest BIOS before swapping CPUs.

I am at loss what to do.

Specs:
Motherboard: MSI MAG Tomahawk Z790 WIFI
CPU: Intel i9-12900K (12th gen is the new one (yes I downgraded), the previous one was an i9-13900K)
GPU: ZOTAC RTX 4070 Super Trinity Black
RAM: Corsair Vengeance 64Go (2x32Go)
PSU: Corsair HX1000i

 

[COLGeek]

Have you re-seated the memory and re-checked the seating of your GPU, power cables, etc?

Even though you only swapped CPUs, you can easily dislodge other components when making such a switch.

 

[TemporarySoil]

I tried re-seating the memory and checking that everything is plugged and something weird happened.

I got it to post with only one ram seated on the fourth slot (when it worked with both on 2nd and 4th slot earlier today with the previous CPU).
I tried swapping both rams and both work but only if I seat one at a time on 4th slot. If I try to seat one on the 2nd and one on the 4th it doesn't post.

I don't understand when they worked fine earlier today? Did I damage the mobo? Both sticks seem fine, they just won't post if I plug both at the same time, weirdly enough.

 

[COLGeek]

I recommend removing the CPU and inspecting the motherboard's CPU socket. You may have damaged/bent pins.

 

[SkyNetRising]

I don't understand when they worked fine earlier today?
Did I damage the mobo? Both sticks seem fine, they just won't post if I plug both at the same time, weirdly enough.

It's quite easy to damage cpu socket pins. They are extremely tiny and fragile.

Make several high resolution photos of cpu socket from multiple angles and show here.
(upload to imgur.com and post link)

 

[TemporarySoil]

The pins don't look bent to me, but I could be wrong.

https://imgur.com/a/Fgy4abA

View: https://imgur.com/a/Fgy4abA


Here, hope the link works.

 

[COLGeek]

Can you add a picture of the underside of the CPU?

 

[TemporarySoil]

After trying to reseat everything I managed to get the PC to post with the new CPU and both sticks.

I'm not sure what caused this? Maybe a bad mount?
Anyway, thank you for your help.

 

[JayGau]

After trying to reseat everything I managed to get the PC to post with the new CPU and both sticks.

I'm not sure what caused this? Maybe a bad mount?
Anyway, thank you for your help.

Could have been several things. Since your pins are not damaged the CPU was probably well mounted all along.

The most likely is a RAM stick not seated all the way (for the motherboard it's the equivalent of a defective RAM module so it won't POST). It's easier to push on the stick in slot number 4 since there is more space there, but slot 2 is closer to the CPU cooler and harder to push. I did this mistake a couple of times in the past and now I always triple check that all the sticks are perfectly well inserted before turning on the PC.

 

[SkyNetRising]

After trying to reseat everything I managed to get the PC to post with the new CPU and both sticks.
I'm not sure what caused this? Maybe a bad mount?

I guess - reseating of cpu fixed it.