I aggree with Jason.grimm wrote:Sounds like it might be a power issue? Is your power supply able to handle the load of both cards?
Jason
Furthermore, you are running a Xeon system and your mobo pci expansion`s are to note here.
GTX580 uses PCI Express 2.0 x16 (Compatible with 1.1)
GTX680 uses PCI Express 3.0 x16 (Compatible with 1.1)
It`s all about your mobo and power supply
Kivanc