I'm having to work on my new desktop again. When I first brought it home I installed an ATI R9 270x video card in it and it would boot but without video. I took it out and used the I5 chips video and that work fine. A couple of days later I installed my older Nvidia GeForce GTS 250 and that seemed to work OK till this morning. This morning it took 2 - 3 minutes to boot and had no Gigabyte splash screen where it says press delete to enter setup, ect. I took out the video card and it works well now. While it's EVGA 550 watt power supply has adequate specs I'm thinking that may be the problem. My old power supply is a 550 watt Corsair, I guess the only way for me to figure it out is to swap the power supply's. My thoughts are "will the Corsair's fan last another bunch of years"
The Corsair has the longest wiring harness that I've ever seen, I guess I can manage it some how.