My brother gave me his old GTX 580 and at first I realized I didn't have a strong enough PSU.
All the fans would spin but nothing would boot up.
A week later with my new 700W psu (all the right connectors) I'm getting the same deal. Everything spins correctly all connectors hooked up properly but no boot.
Take it out -> boots fine. Mouse/KB lights come on, I can hear the HD reading etc.
Motherboard: MSI 770T-C35
GTX 580 2x 8pin connectors (n580gtx lightning XE)
I'm wondering if it's the PCI-e slot on my motherboard though it ran the previous PCI-e 2.0 x16 required gfx card no problem (GTS 450 and HD Radeon 4890)
The card is under warranty so just sending it in is a solution but want to know if it's cause the card is defective first.