Strange PC boot problem

[OliP]

Hi, recently i built my desktop PC for the first time ever, im happy to say it was very successful and i now have in my opinion an amazing pc for my needs.
But there is a problem that has been annoying me, when i press the power button the fans start and the processor light comes on as though it is booting up but then the processor stops and im just left with the fans spinning in order to get the pc to boot i have to press the reset button, the fans stay spinning and the processor starts again and it boots up.

 

[Z][GGY]

power issue strange?? but i'm sure i have seen this sort of thing before but can't remember where

 

[OliP]

It may be a power problem, when i was building the pc i noticed something strange, i plugged in the 24 pin power plug but there was also an 8 pin socket on the board with a cover over 4 of the holes, i took the cover off but my power packs 8 pin plug wouldnt clip into the 8 pin socket properly so i have only put in the 4 pin plug.