Windows 7 - Lost the video on wife's computer

My wife was playing a game and her computer froze. I tried to close it but that didn't work. Tried control/alt/delete...no response.
I ultimately had to resort to hitting the off switch.
When I tried to boot back up I was getting "No Signal" on monitor. I tried it several times to no avail.
I tried changing to onboard video.
I disconnected the dvi and plugged in a vga cable
I tried changing cables.
I tried another power cord..
I tried another monitor.
I can't even get into the bios or safe mode because I can't get a signal.
No matter what I try i can't get a video signal.

This is a fairly old computer with an I3 dual core CPU
4gb ddr2 ram
Nvidia GT8600 video card.

Any Ideas would be much appreciated.

Have you opened the computer up to see if there is dust covering the gpu, a while back on my old computer the same thing happened to me it turns of my Graphics card diesd cause i was'nt taking good care of it, there was so much dust on it the fans could barely move. So if you haven't cleaned it out yet, clean it out, and then test.

I did check that thx.
There was a lot of dust. I cleaned it and tried again.
I don't think its the card.
I took the card out and tried the onboard video but that didn't work either.

On some motherboards there are manual switches that you have to flip to turn the onboard graphics card, on try looking for a switch on your motherboard.

I have the same graphics card as you btw.

Edited.

Make and model number of PSU please? An underpowered, low quality PSU would be my first suspect for taking down the video card and other hardware components.

This should work.

It should automatically revert to the onboard video, when a dedicated card isn't detected.

Are you able to test the card in a different system?

The power supply is 500 watts.

Foxtech

FX-500W-TV2

Thank you to those who responded. It turns out the motherboard died.

My condolences. One of my motherboards fried no too long ago.