To OP, is your computer a full tower or one of the smaller form factors?
Originally Posted by JogaBonito1502
My first guess would be the PSU.
If it is the PSU and you have a smaller form factor, it's going to be harder to find a power supply ... even harder than the tower being a Dell. Either way, I would search ebay for a PSU that's designed specifically for your model of Dell. Dell is absolutely notorious for using specially-designed parts that don't work with any other kind of computer.