The symptoms you are describing mean it could be the gfx card or the psu or a mixture of both unfortunately.
Some more info will help, are you using an add on video card or is it integrated on the MB, is it the stock
psu (power supply unit) and when was the last time the inside of the case was cleaned out including the fans.
Is this your MB at this link http://www.foxconnch...ID=en-us0000319
as it was mentioned on a couple of forums
I came across, if it is and you are using an add on video card try using the onboard video connection but remove
the add on video card first.
If you do have an add on video card please provide the make and model or series number, the issue may even
be caused by a loose connection etc.