Since fitting the new fans on the CPU and case the PC has become so much quieter I can hardly hear it. When I walk into the room for a brief moment I wonder if my PC is still switched on. No more roar from the fans drowning out the quiet parts of a video or film. Hooray! The fan roar really used to annoy me. :( The biggest problem I had was working out how to dissemble the original CPU cooling unit without breaking the tiny plastic parts that held the fan. I suppose a special tool is required to do it easily. However not to be out done, I used 3 thin-bladed table knives simultaneously to form a 3-sided tool on 3 clips to carefully unclip the old fan with no damage whatsoever. I think the change of fans was very well worthwhile and I should have done it ages ago.