[newbe]

I built a PC, maybe a few months ago. It worked fine at first, but after I was on it a short while it would freeze up (my mouse would not work, nor would keyboard) and then it would go to black screen on me. My assumption was that i was overheating...

I built a PC, maybe a few months ago. It worked fine at first, but after I was on it a short while it would freeze up (my mouse would not work, nor would keyboard) and then it would go to black screen on me. My assumption was that i was overheating the processor or something and so it was shutting down on me.
I'll give you specs on machine now so you know what we are dealing with:
Intel Motherboard D975XBX
Intel processor Core2 Duo E7200
2 GB Kingston DDR2 memory, 800MHZ (1gb x 2)
Maxtor diamondmax 200GB SATA drive
GeForce 7100GS 256MB PCI-E video card
Antec Neopower 650 PS
maddog DVD RW drive
and my heatsink/fan I actually have switched out several times in my attempts to solve my problem (which I thought was an overheating issue)
Current heat sink is a ThermalTake TMG i1 heatsink/fan

Back to my story...
So as I mentioned I tried to change out my heat sink a time or two and every time I went and tried to boot up I got nothing. I got power, I got activity from my drive, I got fans spinning, etc. But no Beep, and no boot.
So, my next assumption is that I fried my CPU when it got too hot (which I still am not even sure is what the problem was - if anyone thinks they have an idea please share!!) and I go buy a replacement CPU (same one)
Stick that in and try again. Nada
Now I am thinking maybe it was the mobo, or maybe in my times of cleaning off the thermal material and swapping heatsinks, maybe I used too much pressure and somehow tweaked the connectors on the mobo that the processor sits on - Is that possible to do???
Also, the locking mechanism on the mobo that holds the processor seems really tight to me and I was thinking maybe that its pushing too hard and maybe IT tweaked the connectors.
I really have no idea if my theories are cuckoo or if they may be valid..

I would really like to hear what everyone hear thinks my issue here is....please.

Oh, and by the way, I did double-triple check all connections, and tried to re-seat cards and memory etc, and tried using only one memory stick etc.