Did you use all 8 pins for the 8-pin connector?
Can you test with another video card?
Can you test with another power supply?
It's possible that your power supply is defective.
We can best help you after you create a detailed hardware list in the PC Specs portion of your forum profile http://forums.tweaktown.com/profile.php?do=editprofile at the bottom of the profile page or in your forum signature http://forums.tweaktown.com/profile....=editsignature.