Monitor went out on PC ..but monitor works with other PC?

Your video card is bad, or something else in the computer is malfunctioning.

uh... try a new display card. not sure

Is it your video card? Or is it a software issue?

most likely your video card is bad to ensure that is the problem, try another working monitor on your current computer and see if it works or not it's 99% your video card

it's the actual video output on the back of the computer that is either fried or no longer properly connected/working. if you buy and add a cheap video card you can use the output on it instead.

It sounds like your video card went up or lost its drivers. Try updating the driver first.

Possible problems and possible solutions are these: Overheating. Put your computer on a clean hard surface, and take the side panel off the case. if there is dust and grime allover everything, you should go get some Q-tips and some rubbing alcohol and clean everything off. Make sure the computer is unplugged first please, I don't need to be sued for telling you do do this and getting you hurt. Also turn the computer on with the case open and make sure the fans are running. Bad power supply. If your whole computer shut off like you said, the power supply could be failing. The best way to check this is to look up the wiring diagram on your specific model, and hook it up to a diode, resistor, and LED in series. that way you can see if the output is correct by watching if the LED turn on or not. You can also get PSU testers, but they are expensive. You can get a second PSU, but that takes time and costs money as well. Bad Video Card. If your computer turns on fine, and you hear some beeping noises coming from inside the case, the computer is telling you what is wrong. Get your motherboard manual out, and listen to the beeps. Then look up what the sequence means. Some boards will also come with a seven segment LED display, that will show an error code if there is something wrong. Oh, and you can try putting a different vid card in and seeing if that fixes the problem. Bad motherboard. Your board could also be going bad itself, though that would not be specifically limited to the graphics output. There really isn't any way to test that, aside from getting known good parts and seeing if the problem still persists. That costs a lot of money and time, and you will be stuck with a spare everything if it is indeed the board. I recommend testing the video card, checking for over-heating/ fan operation, and possibly testing the PSU. Do remember that your computer PSU can kill you if you don't check it properly, so if you feel at all uncomfortable doing it take it to a professional. I only say that because if you short the wrong pins, you are dead. There are very large capacitors inside the PSU and you don't want to be their ground connection.

Sounds like a video error. The yellow light means it is not receiving a signal from your video card, which is what your screen plugs in to. I would 1st try opening up your case and getting some compressed air and cleaning out your inside of the case as the video card is most likely corroded with dust. After cleansing and it still does not work, you might think about changing yoru video source or adding a video card if you are using onboard.