Problem with PC

hi everybody ive got a proplem with my pc i think it might be a power problem but im not sure. when i turn on my pc all the fans turn on but the cpu fan its spin a bit than stops and spins and stops and the dvd drive makes a sound like when it trys to read a dvd and on the screen it says no signal. so i turn of the pc and turn of the psu from the back then wait a little and turn it back on after a small delay its starts and everything is bak to normal but i have to do this every time i start up my pc.

ive narrowed it done its not psu, not ram, not the optical, not the hdd, it could be either motherboard or GPU

p35-dq6 mobo
4gb ram 800
e6600 cpu
640mb 8800gts
1tb wd hdd
320gb wd hdd
new vantec 600w ion+2

also when i removed the ram there was no beeps and when i removed the power from the GPU it beeped.

ive got a video
http://www.youtube.com/watch?v=28g8bZ1lROs

well i when the problem started i had a coolermaster psu i bought the vantec a recently and it didnt solve the problem