I have AMD XP 2500+ with Epox motherboard. When I start the computer the VDD volt is around 1,6 volt, and it usually works some time. After some time the mouse pointer freezes or disappear, and the VDD volt has dropped to under 1,2 volt. I don't know if it is a heat problem or if the motherboard is bad. If I let the computer rest and cool down, it works some time.
Cpu is around 60 degree celsius.
See the heatsink on the chiepset, is he sable, if he fry your finger on touch then U can try with replacing it with some with better heat disipation meyby with one with active cooling if U dont care for noise.
For the first U can stick some 80mm fan near chiepset to cool it and to be sure if U need a new chiepset cooler.
Those temps are a little high, but may not be the reason behind the voltage drops. As vulefu states, check the temp of both the chipset and the CPU. Even for an Athlon XP those temps are high (my old 1700 Palomino, notoriously hot, pegged at around 55 degrees while under full load). For the CPU I'd suggest getting some good thermal compound and clean off/reapply the stuff. make sure not to put it on too thick, just a pea-sized drop is suffiecient for the old Athlons (due to the exposed core).
Also, as is the case with all instability issues, I suggest some hardware stress testing to try to reveal any weak components. Memtest 86+, prime95, lucifer, etc. If it runs these tests for a good 8 hours, the hardware's probably good, look at the drivers.
I use this computer only for DC++, so it runs usually always. The first thing to happen is the mouse pointer freezing or disappearing, and that has happened now. For now I dont see how hot it is running, I don't have any program that reads the temp. But always when it happens, the vdd volt is very low, if I restart, then bios show it in red. But if it goes hot, does it affect the volt? I didn´t want restart it yet, because I wait for one file to get downloaded.
When I last shut down the computer and it rested for 48 hours, then I started it again, so mayby after 12-16 hours I got the problem for mouse pointer to disappear, otherwise the computer runs still, and probably this is caused by the drop of voltage. All other voltages seems to be ok.
Those temps are a little high, but may not be the reason behind the voltage drops.
I said all that stuff about reapplying thermal compond to prevent those high temps and extend the life of your PC, preventative maintainence.
I suggested the stress testing as a method to try to figure out if some particular component is flakey. I definately think it's the power supply or the power-handling circuitry on the motherboard, but this is just trying to recreate a similar situation outside of Windows to rule out drivers.
Now I cleaned between cpu fan and heat sink. Now when I have the side of case open, the temp is a 47, if I close it then it begins to rise, it was at 54 then i remove the side of case again, now it has dropped to 47 and has been so for a couple of hours. And the volt is at 1,3-1,42, mostly at 1,36. It is still low but better than before. So the heat has to do partly with the volt.
Before I cleaned between fan and sink, the heat sink was very hot, I couldt touch it with my fingers but not much more.