So recently put together my old computer and right now everything is in besides the hard drive. The problem is that the computer powers up (fans turn) but nothing appears on the monitor. Also I am unable to turn it off with the on/off switch only the manual one on the psu. Any ideas?
If you aren't getting post, it could be any number of electrical issues. It is certainly a hardware problem. Solutions could range from trying different sticks of RAM to making sure the motherboard isn't grounding on the case.
Try unplugging the main power cable and pressing the power button a few times while unplugged. Wait a bit and try again.