My computer tells me it's overheating, but I know that it's not.

January 7, 2006 2:25 PM

The temperature sensor on my motherboard is going haywire! With an ambient temperature of around 30° Celsius, Motherboard Monitor is telling me that case temperature is fluctuating between -50°C and 50°C, with CPU temperature fluctuating between -125°C and 110°C. The sensor is obviously fried, but what can I do about it?

The computer is a 2.8gHz Pentium 4, about 18 months old, built for me with off-the-shelf components. Motherboard is a Gigabyte 8S648FX-RZ, with firmware updated. OS is XP Home sp2 (updated). I suspect that the sensor problem was causing random shutdowns. I've now stopped the automatic shutdown, which seems to have resolved this issue, but I suspect that this problem is why I frequently have trouble booting up (computer thinks that the CPU is overheating so refuses to boot up?). I live on an island in the middle of the Pacific Ocean, so service options and spare parts are a long, long way away. Grateful for any suggestions.

posted by Tawita to computers & internet (3 comments total)

Check through your BIOS for the temperature sensor info. You may be able to completely disable it from there.
posted by Kickstart70 at 4:00 PM on January 7, 2006

A software sensor monitor isn't really a reliable indicator of anything as far as sensors are concerned; unless you're seeing these wild temperature variations in your motherboard BIOS, it's more likely to be MBM simply not peeking at the right values to get a sensible reading. Even if the BIOS is seeing dodgy readings, a motherboard generally shouldn't take them *that* seriously.

Also MBM hasn't been maintained in quite a while afaik; you might have better luck with SpeedFan, but there's no guarantee it'll know any more about your motherboard sensors than MBM.

Bootup problems can be caused by lots of things, can you be more specific about symptoms? If it's mostly at initial poweron, you may want to look at replacing the PSU, especially if you're running a cheap noname, doubly so if your mains power isn't the cleanest. Your motherboard sensors might be able to give you an idea of the voltage levels on each rail (12v, 5v and 3.3v are the main ones; measured values should be within 10% of those, and preferably quite stable).

Power wise it's also a good idea to check the motherboard for doming capacitors; these are fairly common especially on older boards, and can cause all matter of similar problems prior to failing outright (it's a sign of the electrolytic fluid boiling/outgassing). These are replacable with a soldering iron, equally rated replacement caps and someone who knows what they're doing.
posted by Freaky at 7:04 AM on January 8, 2006

I'd second what Freaky said. Check out www.badcaps.net for more information. I was experiencing the same problems you were and opened up my computer and noticed all the capacitors leaking.

If this is the case, you may be entitled to free repair if you pay for shipping both ways. Contact gigabyte and see if they'll help.
posted by bigdave at 2:14 PM on January 8, 2006