Computer Keeps Shutting doen and monitor says no signal

[prophetstruth]

I have an e-machine c2280 with a GeForce FX 5500 GFX card. Every time I power on the computer it stays on for about 2 minutes and then shuts down. Also the monitor says No signal. What could the problem be

 

[das_stig]

Graphics card is probably overheating, try cleaning the fan, sorry to say e-machines and FX cards are at the low end of the technology and reliability ladder.

 

[JackNaylorPE]

Something shutting down on thermal overload. Download HWMonitor and start on bootup watch temps.

Blow out all dust from case, GFX card housing and CPU HS

 

[jsc]

Our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-posting-boot-problems