Computer shut down and wont start up at all.

[trivialdeath]

Hello, i have a problem with my computer i was playing APB (All points bulletin) and my CPU fan was roaring so i was about to shut off my computer and it did it itself, i thought it was the Gcard Nvidia GTX 260, i took it out and put in my old one 9800GTX+ and it still wont start up, there is power because the ether-net port has its orange light up and the front of my comp has a light which goes on so im guessing its the CPU but can anyone give me their opinion?

 

[trivialdeath]

Also after i had tried the old gcard i took the far off of the processor to let it cool faster and got rid of some dust the processor was scorching hot, not sure if this helps or not though.

 

[geofelt]

Your cpu probably shut down to protect itself from heat. You might want to remount the cpu cooler.

Push pin coolers can be tricky to install.
A bad installation can lead to higher temperatures, and even cpu throttling.
With the pc powered down, gently rock the cooler to see if it is on solid, or if it wobbles a bit.
Push pin coolers are best installed while the motherboard is outside of the case.
You need to be able to look at the back of the board to verify that
all 4 pins are completely through and locked.
Play with the pins on the cooler first, so you can see exactly how they work.
Read the instructions that came with your retail cpu.
When pushing down on the pins, do a diagonal pair first.
If you don't, it is hard to get the last pin in.
Don't forget to clean the parts and reapply fresh thermal compound every time.
Don't try to reuse the TIM.
Rubbing alcohol is OK as a cleaner.
I use a paper coffee filter to clean with because it is lint free.
Any name brand TIM should be OK(as-5, Mx-2, etc.)
When applying the TIM, don't use too much, because it can act as an insulator.
Don't apply too little, either, because it won't spread and fill the microscopic
imperfections in the surfaces. A dollop about the size of a grain
of rice should be about right.

After cooling, I don't know why it would not start. Sometimes unplugging the psu will cause a better reset of the bios.

 

[silky salamandr]

It wont boot into windows or it wont post? Theres a difference. If you can get it to post, go into your bios and monitor you cpu temp just like the last dude said. If its getting unusually hot, than you know you have a cooling problem and just like the last dude said again, re-seat the cooler and do it right. He laid out the instructions down to a t.

Whats your specs?

 

[trivialdeath]

well my computer wont start up at all so i cant go into the bios and what not, i also asked a friend who knows a bit about computer technical stuff he said it maybe the power supply? im not sure tbh but i will try what geofelt said when i either buy some new thermal paste or find some in my house

also my specs are
Win XP 32bit
Nvidia Palit GTX 260
AMD Athlon(tm) II X4 620 Processor 2.6Ghz
4GB DDR2 RAM