What case and fan setup are you using? I don't think my northbridge get's that hot. I have a thermal probe on the northbridge heatsink and it's at 33 Celsius right now as I type this with my computer at idle. Definitely not burn worthy temps, like your experiencing. I don't think I've ever bothered touching the southbridge so I can't comment on that.
@ Orick - Try using Hardware Monitor instead for temps and then tell us what TMPIN0-2 says.
On idle, temps are:
The ambient is about 20C. I am feeling the southbridge and northbridge with the back of finger. Southbridge definitely hot enough to burn. I can't keep my finger on it long. Northbridge is not as hot but still pretty warm.
I originally had the fan in front of case as intake. So it blew over the southbridge a bit. The southbridge was not hot then even running Prime95. Then I moved the fan to the back as exhaust to be close to the CPU. That's when I started to notice how hot the southbridge got. I can move the fan back but I am planning to get a 5850 GPU which won't leave any room for the front fan.
Also, I am running 2 harddrives in Raid 1. Maybe that makes a difference since southbridge is the SATA controller?
So far, I have been a bit underwhelmed by the mobo/case combination.