I have had to build my PC over again, so I ask you, did you re-seat the CPU? Is it locked in? Then install your fan. Check all wires to the motherboard and make sure they are connected. YOu might have a diagram that came with your PC. Check you hard drive cables. ARe they seated. You say you cannot boot into the bios, that sounds like a CPU problem. You might have unseated it when you messed with the fan. Try re-seating it with fresh thermal paste as mentioned above. Hope you get it fixed. IF you do, I would recommend getting a Radeon graphics card. I had nothing but problems with the Nvidia, especially in Vue.