Posted in another thread (please don't create duplicates for related topics):
My graphics cards fans are spinning just fine and and looks like its working and when i plugged in the pins for it i put a six pin in the pin slot and i put another six pin in the eight pin slot is this safe to do and another question if it is after i did that i used the motherboards outputs so should i not use that or will my graphics card be work the same as if i put a dvi in the graphics card output
You need both the 6 pin and the 8 pin, or the card will not fully power on.
If you have the display connected to the motherboard, it will use the iGPU for rendering, and won't be using your nice fast GPU.
Stuff in the POST problems sticky may be useful: http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems