I recently acquired to Geforce GTX 670 GPUs to run in SLI. I was running one with no problems for a while. I got a new one today and tried to install it. I may have made some error because when I turned on the computer, the fans on both cards went up to 100% for some reason. My monitor would not work either. I took out the second card and my computer worked fine. I tried putting it back in and I realized that I had not plugged in the power connectors completely (I think). When I pushed the 6/8 pin connectors in entirely, the fan thing stopped, but my monitor still did not work and my mouse and keyboard did light up, they had previously. I took out the new card again and found that did not fix the problem this time. The fans (case/CPU) are still spinning and my USB network adapter lights up. I tried taking out both cards and using my intel graphics, but nothing changed.