Computer is making a constant humming noise. It does not stop. Check the wires near the power supply fan and all looks OK. Is there anything else I should check?

Hey Panii,
Yeah there are lots of things you can check. The two significant ones would be the possibility that it's your CPU fan that's making the humming sound or the hard drive that is making it. CPUs will "fry" pretty quick without a cooling fan (especially the newer ones) and once your hard drive quits spinning you've lost your data (expensive repair possible). It's my understanding that the most common fan to begin to make noise is the fan at the back of the power supply. If you have another case cooling fan, they are also pretty cheaply made little gizmos too.
If you're comfortable with opening up your case, you can probably discover the "noisemaker". Make your own stethoscope with a piece of rubber tubing and put one end in/near your ear and the other near the various devices in the case. Watch out for static discharge, not from the machine, but from you. You ought to be able to tell where the noise is coming from, then post back and one of the smart guy/geeks will advise you on what to do about it.
Peace and good luck and post back.