I was upgrading my friends pc, a dell 3847. I replaced the psu with a corsair cx600m. We scavenged an old nvidia gpu (I believe a 8800 gt) and we plugged it in using DVI. The monitor said that it was in power savings. So then we put in a msi gtx 660, using the HDMI port and it STILL was in power saving mode. However, when we unplugged the gpu's and ran it on integrated it worked. How can we get this to work?