My graphics card is not working even though the fans are spinning, I purchased a second card, that didn't work either. I even bought a new motherboard ,thinking the pcie slot on the other motherboard was broken. I know the power supply is sufficient because I used a power calculator to see if it would work and it said my psu was more than enough. What should I do?
First motherboard: mcp73pv
second motherboard: g31m gs r2.0
first graphics card: pny gtx 460 768mb
second graphics card: radeon hd 6850 1gb
Do these system boards work with onboard graphics? You may need to disable onboard graphics in the system bios, reboot, then install the graphics cards before it will work. When the machine turns on, do you hear the normal post beep? If you leave the computer on when this happens, can you press number lock or caps lock and see it light up on the keyboard? If it does light up, that means it is booting up to windows, and just not getting video. Do these cards require extra power connections beyond what the pci -express gives? If so, try different power connectors if your power supply has them in case one is faulty. Also, what kind of power supply is it that you have? Even though it may say it provides a certain wattage, not all power supplies are created equal and may not provide sufficient voltage on the different rails. I am not a power supply expert however usually cheaper power supplies like the ones that come with a cpu case are generally lower quality and may not allow power hungry devices like video cards to work correctly.
One thing you could try is doing a minimal boot as well. Disconnect everything except for cpu (and its fan), 1 stick of ram, and the video card to see if it will POST. If it does boot, shut it down and start reconnecting devices and cards one at a time to see where it fails. If it will not boot with just the minimal boot, the problem has to be either system board, ram, video card, power supply, or cpu.