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

It is quite possible that it is that PSU going through a slow death. I'd replace that Craptech PSU with something else now! Look for: Antec, PC P&C, OCZ, Corsair, Enermax, Zalman, BFG, or Silverstone/Seasonic (unless in a 220v area). The fact that you have to flip the power switch on the PSU means it's dying. Vantech is not known for any quality PSU's. A good quality 550W is more than enough for that system (with a little extra for upgrades).

ive got a video just to show what im talking bout with the cpu
http://www.youtube.com/watch?v=28g8bZ1lROs

is there any way i can know for sure that the motherboard is the problem and can it also be the graphics card the problem.

ok ill give it a try