Computer won't boot when adding fans

[eslam1291]

So Ive got this R9 280x as a gift from my brother. my PSU was too weak so i went ahead and bought a new one 750w so i plugged everything in the psu the gpu and i went ahead and booted the pc first time it was without plugging the fans to the psu the pc worked and started but when i tried plugging in the fans to the psu the pc wont boot at all

Is the problem because i don't have enough watt?
or what i don't really get it at all...

 

[faalin]

First what are your system specs so we know what we're working with.

Second what plug ends do you have on your fans? Are there 3 pin fan header plugs as well as 4 pin molex?