Question No signal on monitor while pc running

[Kozer1]

I tried to change my cpu cooler, everything went good, I turn pc on, pc is running normally (fans are on, pc isnt restarting, went though POST normally) but no signal on monitor. I have tried 3 different gpu's, 2 monitors, 3 cables, no difference. Everything is working on another motherboard. That's why I thought its mobo pcie's problem. Ive sent mobo to shop, but they checked it and it normally gave video output for them. They have sent it back to me but its still not working. I have also tried different ram, but no results. So last thing that can cause it must be CPU, but is it possible that cpu is broken, but successfully runs through POST and gives no video signal? Is there anything I can do besides changing cpu? Also, strange thing is that when I take out all ram sticks, it doesnt change anything, pc is normally running and isnt restarting (like its running exactly the same when ram is in). Unfortunately this little speaker isnt working so I dont know of there are any beep codes, but i think there are not because pc isnt restarting. I also did reset bios. What else can I check?

 

[rgd1101]

full system spec? include brand and model of the psu

 

[Kozer1]

Oh sorry, I forgot. i3 12100F, gigabyte b660m ds3h, silentiumpc fortis 5 dual/stock cooler (i checked on both), 2x8gb 3200mhz cl16 adata xpg gammix ram, asus dual rx 6600, kioxia exceria g2 drive, Silentiumpc vero L3 600W 80+ bronze PSU.

 

[Kozer1]

I can add that after few seconds of pc running, cpu isnt heating, its cold like its not running. Is it possible that cpu died?