Cpu Problem..Please Need Help

Im currently building a pc, this is my second build and i ordered a cpu that didnt come with a fan/heatsink and im pretty sure it had no thermal paste on it well i put it into my computer and just found an out amd fan kicking around on it. Here my problem when i turn on the computer it doesn't really go on the fans just twich a little inside and that is it, is it because of a fault power supply, is my motherboard faulty, or is the cpu having a garbage fan and no thermal paste (i think) just causing it to shut down really fast?
Please Help..