Computer wont boot.

Dskwirba

Honorable
Jun 13, 2013
2
0
10,510
My Computer will turn on for a millisecond then right back off. i have tested my power supply and then plugged another power supply in. i have tried with only bare minimum, i.e. no graphics one ram, no cd drive, ect. please help. it will boot if i just have the 24pin atx plugged in, but as soon as the 8pin is plugged in it just tries to start but fails. i have my motherboard out of my case on a mat. it is not the button i am starting it from the board.

Here are my specs:
-GIGABYTE GA-990FXA-UD5
-AMD Phenom II X4 980
-COOLER MASTER Hyper N 520
-XFX Core Edition PRO650W
-HIS Radeon HD 6850
- 4 CORSAIR 2GB DDR3 1333
 

Dskwirba

Honorable
Jun 13, 2013
2
0
10,510


i reset the cpu and still the same thing. its like a car trying to turn over/start but it cant.