I've seen lots of posts over many boards, but never any answers.
I'm using the stock heat pipe on the Maximus Formula and every now and then I'll get a system shutdown/restart with the message "South Bridge overheat" message. I've never seen the temps over 50 degrees C in any monitoring tool. The BIOS shouldn't be interfering until temps hit 90 according to the COP EX settings in the BIOS.
S.B. is set to lowest voltage, or Auto, and N.B. is 1.41.
This has happened over the original BIOS and the new 907 BIOS.
I thought you're suppose to stay under 40C or something? Of course this should be different for every motherboard so I wouldn't know. I've always thought the general rule of thumb was to stay under 40C for idle.
I would agree on the "40 degree" rule of thumb, but this is the only mobo I've ever had that reported the temps on the N.B. and S.B. and they've never been below 40. I'm even using my 2nd Maximus and it's behaving the same way. It's so hard to trust temp readings on PCs anyway, I'm not sure how much stock I should put into it. You would think that temp sensors wouldn't be a major problem for PC/chip makers. Is it really that complicated?
I did a lot of research on x38 chipset temps because mine runs pretty hot at stock (266fsb) while only gaining 3c idle at 400fsb.
Answer: x38 chipsets run a good bit hotter than the p35 - the thermal "limit" from intel for a shutdown is 92c (northbridge).
With my board adding a 120mm ultra kaze intake fan dropped the mobo temp by 6c which is a lot so fist make sure you have an ample intake cooling.
Next instead of shipping the board back I recommend you reseat the heat-pipe array with a quality non-conductive thermal paste. While I'm planning to do so with my board I especially think a bad heat transfer is causing your problem since it was the southbridge. I just don't think its getting much thermal transfer. I'd check with asus first to make sure that this won't void your warranty in case the southbridge is actually defective.
Also 40c+ isn't uncommon for x38 boards as I stated above they don't shutdown till 92c with the assumption by many (including myself) is that they are fine running up to 70c but preferably around or below the 60c mark.
What did you use to measure the NB/SB? Was it built in BIOS or is their a software program that can do it. I use HWmonitor and think it reports my NB, but I know for a fact it reports my E2180 temps off (15C deal)
I use the hardware monitor in the BIOS as well as the Asus Probe software in Vista. Both seem to report the same temps. But...the BIOS seems to think my CPU is between 0 and 15 degrees. So I'm not sure I can rely on any of their readings.
My system is now running at 425x9 with 1.456 volts, NB @ 1.41 volts and S.B. all on auto (as low as they will go). I haven't had any issues lately with chipset temps, but they are still hovering just below 50.
I had the same problem with Asus probe software in Vista, (Does it in xp too) go to the asus forums, you'll see its a common problem. While my system did not shut down the probe software kept jumping around on my NB and SB volts, Before i even overclocked! Giving me warnings and annoying the crap outta me.
I got Everest and all that went away, best Hardware monitor out there in my Opinion.
I have no idea why, but my overtemp messages have not come back in quite some time. CPU still reads crazy-low, but I can read the die temps via Everest and the LCD on the keyboard so I'm ok there; no need to RMA the board.
I tried to get to 4.0 GHZ stable the other day. I had the CPU @ 1.5v and NB @ 1.61 v. It wasn't stable after 1/2 hour of gaming, but the chipset temps were in the low 50s. That really doesn't seem nearly as bad as they were before. Maybe it was the ginormous fan on the new side window...