My Dell Dimension 9100 has a annoying feature, especially when used with Media center edition. To have the proper "10 foot experience" you can put your PC into standby mode by pressing the power button on the media centre remote. This works but for some reason all the fans in the pc are still blowing so it sounds like the PC is still on (even though the power light is flashing so it is actually in standby).
After a bit of research it seems the Logitech wireless keyboard and mouse could be the reason for this.
If you want your CPU fan and power supply fans to go off during standby, please follow these simple steps...
Goto: Device Manager, Keyboard, in Keyboard properties goto Power Management, Uncheck 'Allow this device to bring the computer out of standby'
Follow the same steps for the mouse properties...
Then follow the same steps for the "eHome Ir Remote" properties...
Each of the Mouse, Keyboard and virtual Ir Receiver have to be unchecked for the fans to go off in standby.
Please note that doing this will not allow you to bring your PC out of standby with either the keyboard/mouse or remote meaning you will have to use the power button on your PC to bring it out of standby.
The good news is that Media center is smart enough to bring the PC out of standby if you have a TV program recording scheduled and the put it back into standby afterwards.
Result, the noisy PC in the corner behind the TV is silent. I am looking into replacing some of the fans inside the PC with quieter ones so that even when the PC is on its not so disruptive.
Zalman make almost silent fans that do just as good a job as the noisy ones but are less than 20 decibels which is effectively silent inside a PC case. Just have to figure out which of the 3 fans in the 9100 is making the racket now...