the heat is what is damaging to the bulb and drastically reduces the bulb life. your ballast is also affected because like all electronics, heat is your worst enemy. plus if your PC set is not on stands you get in to heating the water. if the sound is really that big of a deal, look in to getting some new fans. a lot of manufacturers use cheap fans. www.thermalfx.com
is an excellent site to start looking for fans. most PC light sets use printer fans. the crew at thermalFX is great, i have talked with them over the phone and they were a huge help.