So, I am having some difficulty. The PSU for the computer had been really loud as of late and we were worried that it might break. So, we replaced it.

I received the new PSU today, took out the old one. (had a little trouble removing the connector near the CPU). Placed the new one in connected everything. Tried powering on and got nothing. there was a slight burning smell.

Put in the old PSU back in fearing it was DOA. Turned the power on. Nothing again, slight burning smell returned.

I think I might have fried something.

Is there a way for me to diagnosis this past I think I might have fried the motherboard?

Computer components:

OLD PSU: COOLMAX CT-450N ATX12V 450W Power Supply 115/ 230 V UL, CSA, TUV, CE
Motherboard: ASUS P5PE-VM LGA 775 Intel 865G Micro ATX Intel Motherboard
CPU: Intel Celeron D 347 Cedar Mill 3.06GHz 512KB L2 Cache LGA 775 Single-Core Processor
NEW PSU: Antec earthwatts EA430 ATX12V v2.0 430W Power Supply 100 - 240 V UL, CUL, FCC, TUV, CE, CB, C-tick, CCC

I would have posted links but, my post count is not high enough.

I am not quite sure, but I know dell used proprietary psus and I think packard bell did at one time also. Anybody want to comment on this?

This is a Home built machine, I bought parts from Newegg.com

I was pretty sure the new PSU would work fine. I was really upset when I smelled the burning. After removing the components, I found that it was the mobo.

Ordering a new one now.

Do you think my having trouble removing the old PSU could have been the cause of the problem?

After removing the Heat sink and the CPU, I found the thermopaste hard and dusty. Would this be causing the problems I am having with the system?

While you are waiting for the new board, you can reinstall your heatsink/fan with new thermo paste and try again. You might have just know the heatsink/fan loose while you try to remove the "hard to remove" connector the first time or you might have plugged the connector on the board the first time and took out the board.

Good luck and let us know how things turn out.

I applied new thermal paste to the CPU and heat sink, re-attached everything and it was working fine.

Now, the computer won't start up for longer than 5 minutes, and each shut off makes it last less time.

Yay! I double checked the cpu fan and it was a little loose. Everything is honky dory!

scarey at it
close one there