PSU, CPU, Motherbord need desperate help!

Hi Guys, new to this site and hoping to find some help!
I have an older computer (p4 3.2 with HT) one day the computer froze but when i shut it off to turn it back on, nothing happened. The fan never went on and the computer didn't post. I think I tried everything and now I'm going desperate. I got a 2 new motherboard, new RAM, tested the cpu in another computer and still nothing. When I plug the power supply, the Standby light on the motherboard goes on so I'm guessing the PSU is good. I tried jumping the power pins in case my power button was defective and still nothing! I tried just plugging the motherboard and cpu (but not components such as HD) to a different power supply but still the CPU fan doesn't move (Which I also replaced). I really have no clue of what to do next. Any help is appreciated.

Thanks!

First replace the Power supply,If that doesn't do the trick, Then It would probably be the motherboard... Any power surges in your area ?

I just changed the PSU and I tried 2 different motherboards without any success

Well , If you tried 2 other motherboards , then your problem is probably the CPU.... it might be fried...

I tried that aswell! nothing is working! I have never been so confused!!!lol

Try to test each peace of hardware in another computer to narrow down your problem...Also check computer case power button and reset switch, that they are not stuck.
next thing I would try, I would start fresh, New / another case... then Motherboard and CPU... and so on..