Ok, I have this older computer im tryin 2 fix. Ive made some progress on bringing it back to life. First off i switched out the PSU, b/c the old one was dead... So with some power going to the LED's and MOBO, i thought that was it. But then i saw i needed a 12V 4PIN Square connecter b/c of my mobo form factor. So, now the mobo should be getting the correct amt of power from the psu. So, i got one led on the mobo that lights up and the front led lights up. However, the CPU fan doesnt start, HDD disk do not spin either. Nothing happens at all.

Tryin to find the prob. Im thinking it might be the cpu... I saw on sum other forums that when the cpu is dead, then nothing happens at all. Is that true?
Thanks for any help in advance.
System:
Emachines T3828
-internal all standard except PSU