Here is a tip which does not take much tech knowledge to extend the life of you Tower, and remove some excess noise coming from the fan.  You will need a can of compressed air (Air Duster) sold in most computer stores or from Amazon.  It should come with a tube so you can direct the air better.  Yes, you will need to install it into the exhaust of the can.

First shut your computer and unplug the electrical cord.  If you have the room to turn it sideways, you can leave the other cables plugged in.  Now remove the 2 or 3 screws holding the left side (front view).  Slide the side panel exposing the guts, including the cooling fans.  I start off by blowing the air from the back of the power supply, them the CPU cooling fan.  Let the dust settle (do NOT use a vacuum), and you can use Q-Tips to remove the settled dust.  Now insert that panel, tighten (finger tight) those screws, insert the power cable and your done.

I do this twice a year, Mindblower!