My computer seems to hum the warmer it gets. And it can get pretty loud. Could this be a problem with a fan. Do I need to buy a fan? Which one? I have cleaned the inside of the computer, but still noisy.
Could be a fan, but a normal fan noise is not an issue. Lister to where the noise is coming from. If it's a power supply fan, may not be a good idea to replace it yourself. Any other fan, the type depends on what fan and what size it is.
Depending on the fan, it shouldn't be difficult. Most fans come in standard sizes, usually 80mm or 120mm. It's usually just a few screws and a small 3 or 4 pin wire lead that attaches to the motherboard. Just open the case and take a peek.
Unfortunately, if that's the only fan to the outside of the tower, it's most likely the power supply fan, in which case it's safer to just change out the power supply.