Cpu fan slowdown when clicking on screen?

[mrtauntaun]

Hey all. I am trying to get a pc up and running, and frought with multiple problems. The root I believe could be a cooling issue. Whenever I click on something on my desktop, the start menu, open a window, anything slightly taxing, the cpu fan slows down for an instant, then speeds right back up again. This happens every time, it's most consistent.
System specs: Windows XP Pro SP2, Gigabyte MB, P4 3.0 Ghz socket 278 (I believe), 1 gb ram. The heat sink and fan are stock that came with the cpu, probably a year old at this point. thanks!

 

[Ste]

Theres is no socket 278.

You mean 478.

Whats your power supply and fan setup.

Case temps would be nice.

 

[mrtauntaun]

Yes, 478, sorry, typo on my part.
The case temp at the moment is quite low at the moment, as I have the case open after installing the cpu and never closed it up as this problem started after i put it together. Power supply is an atx 350 watt. The heatsink and fan are the P4 OEM stock, I have multiple case fans both on the case itself (2 fans there) and on the case panels (2 fans there, though they are currently disconnected as I have the panels off).