Computer failure

Well my guess, from the little information you provided, is that it is the video card, if you have an onboard video card (as in no external card, you can still add a separate card, though it might have to be turned off in the BIOS, which can be tricky without a monitor, or there might be jumper switches you can use for that. That being said it isn't easy to diagnose your problem from the data you provided. More info such as what exactly happens when you hit the power button, are there any beeps, what does it sound like in general, what colour is the light on the monitor.

Your motherboard give sound beep once or more? In other word, this can mark your computer something problem. First time is check all equipment, and see the cable. if the light on your monitor is blinking then it's good sign on your monitor. Do you check your VGA-card? All pin must connected with motherboard without loss one pin.

Hello clrumfelt!!! Seems to be something mystic happening with your computer currently. Don't you get any signal at all on your monitor? Don't you even get any signal at the beginning of the start up or it disappears when the windows start up? The detail you gave don't seem to be too much comprehensive. If the CPU lights are on and you cannot see anything at all on your monitor, then its all about the connection of monitor I think... Last time what happened with my computer was that, there were lights on the CPU, and on the monitor it displayed many random colors. It became fine when I pick out the RAM and inserted it again. I was so much afraid with the problem that I tried this and that and finally I found that one of the piece of the two RAMs I had been using had damaged. And when I kept the single RAM it worked well again. And I had to replace the damaged RAM. Well I am no any expert. I just told the problem that happened with mine. Try it, sometimes, the shooting in the dark can also get your enemy down. Anyway wish you to get your computer well soon...Good luck