Question : Monitor loss signal

I got problem with my computer, after i on my computer around 20 minute (sometime more sometime less), the monitor goes blank, no signal from my VGA card to my monitor.

I use Intel DG-33BU motherboard and NVIDIA PCIE card .....
How to check which one is failure ??

Answer : Monitor loss signal

check the temperature for the card - is the fan running? if not, replace it.
http://www.almico.com/speedfan.php