Computer wont post after new MOBO was installed. Whats fried?

Freecity

Prominent
Jul 18, 2017
2
0
510
I have an older prebuilt from a friend that was broken. It would only turn on if the 4 pin was unplugged and of course wouldn't post because of that. I thought the MOBO was fried so i replaced it with one i had on hand. The PC would start up fine with everything plugged in but still wont post. I've tested it with a different PSU and video card but it still wont post. I don't get any error beeps with or without RAM either. Does this mean it is a RAM problem or a fried CPU? Thank you for help and if you have any questions I'll gladly try to answer them.
 

Freecity

Prominent
Jul 18, 2017
2
0
510

Was afraid of that. I will test ram first somehow.