PC doesn't boot up. Year old system

TuPP3

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Mar 24, 2009
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18,510
EDIT: See the bottom line

I just came home, and tried to turn on my PC, it didn't start. I opened case to see motherboard light signals, red means there is power but PC is not turned on, when light is green PC is turned on. No lights. I plugged and unplugged powercable, I got red light. When I pressed power button, green light flashed for split second and fans spinned few times and then both lights went off.

Took all cables off and begin to narrow down problem. First, I changed my 450W corsair to my old 200W PSU (I didn't connect GPU extra power cables) and got same resoult.
I have now disconnected all unneccessary, so there is now: Processor, 1 ram and power switch cable to MB and MB is on carboard box.
PC has started 2 times while narrowing problem until I manually shut it down, but after few part changes it doesn't boot anymore even now fully stripped.
Can it be MB problem? I think there is some kind of short circuit and some fuse is turning power off.
I found that I had put usb cable to motherboard wrong way, cable was only in top row, when I removed that computer started 2nd time but doesn't start anymore(same split second shut down).
I have tried to clear CMOS, same.
Btw. Last time I shut down computer, windows didn't shut it down(Only killed explorer.exe) so I needed to shut down computer from powerswitch.

MB: Abit IP35
CPU: Intel E8400 (3,4Ghz, stock cooler)
GPU: HD4870 512mb
PSU: Corsair 450W
RAM: 2x 1Gb OCZ gold

I was told that 450W is insufficent PSU for my GPU, and that may have damaged my motherboard. Could it be? I have runned 9months with this GPU, not a single crash or freeze, even many hours playing under 100% of GPU stress.
Does warranty cover this possible MB damage?(If I don't mention any "wrong" usage ;) )
Or could it be CPU?

Also, if I have to buy new PSU, does 750W use 750W regardless of system components, or does system draw necessary amount only? Because 450W costs about 1,5$ per 24h so, that's a lot. So would 750W cost about 3$, or the same amount last one did?

EDIT: I figured out the problem, CPU heatsink wasn't seated correclty, so I had to push it down with my palm to get boot. But one little problem still exist, how I get heatsink to seat correctly? Do I have to remove and re-insert it?
 

TuPP3

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Mar 24, 2009
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Yep, I now took off heatsink, but how do I get that thermal paste off? It has dryed, it was original thermalpaste sticker came with stock cooler.
I think I'll buy Zalman or ASUS coolers, they look neat :D

EDIT: It wasn't as dryed as it seemed, it came off with toiletpaper, it does have light stain still, does it need removal with alcohol or so?
 

TuPP3

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Mar 24, 2009
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Well, I reinstalled my old cooler back, but same problem persist!
I'm not able to turn pc on even pressing down cooler.

I didn't spot any damaged pins in my socket... What could be causing this?
 

TuPP3

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Mar 24, 2009
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So, I'm going to buy new motherboard, any suggestions? Preferably P35 chipset motherboard so I don't have to re-install windows. Suggest other chipset motherboards if they are compatible with P35.
Abit IP35 isn't sold anymore (In Finland)