Odd PSU Problem! Need Help ASAP.

[rideblitz]

Something very odd is going on with the PSU. first the computer would only come on for a second or two then shut off. so i got a new mobo from a friend but my windows cd isn't working, so i reinstalled the old mobo, but accidently left the 4-pin p4-12v header plugged in on the new mobo, the only thing, and now the old one fires right up. if i unplug that header from the other mobo it won't work, but aslong as its plugged in it does. by the way the old mobo doesn't have that p4-12v header. is there a way to make the PSU work with out having to have it plugged into the other mobo? thanks!

 

[RealBlackStuff]

If you have an Intel P4 or AMD64 CPU, those cables MUST be plugged in.
Fill in your PC specs under 'User Profile', top left any page, so we can have a look.