Northbridge cooler too hot?

Hi all,

I have this dimension 5150 and was curious about its normal operating temperature. Is it normal for the small heatsink to the right of the cpu to be extremely hot. Just touching it would give a small burn. The cpu cooler is very cool in comparison. Windows is sitting at its desktop and no screensaver so the pc isn't really working hard at all.

Would such a high amount of heat reduce the life of the computer? Can I do anything to keep it cool. Changing heatsink, adding fans... Will that sort of thing void dell warranties?

thanks,