There's a post floating around here somewhere with what to do to check something like this, but I don't have it handy.
Short version, disconnect everything but the PSU to motherboard/cpu, the cpu fan, and leave the RAM in. Plug in only the power switch connector. And a speaker if you have one. Disconnect the monitor, pull the video card, disconnect all drives, etc. Unplug everything else from the motherboard.
Power up - if the PSU comes on and stays on, power off and try the graphics card and monitor, repeat...
Double check your RAM, physically remove it and re-insert. Try with only one module in place.
If no joy with basic config, have to try with another PSU. Also check PSU switch to make sure it's 110V - assuming you're in the US.
do you see the lights on the motherboard ?
if yes, then make sure that the PCI Graphics card is pluged into the Blue (x16) slot. also assuming its a toughpower PSU plus the PCI 6 pin cable from the RED ports to the graphics card