joeguy3121 wrote on 2022-09-08, 22:27:
darry wrote on 2022-09-08, 21:57:
A 400MHz Celeron should run at 2.0 volts. 2.6 volts seems a bit high, as in 30% higher than nominal. I haven't checked the datasheet to see if that is "tolerable", but it definitely won't help thermals and may impact stability as a result.
Also, the CMOS battery is dead .
Finally, and possibly most importantly, 5.0V, 12V, -12V and -5.0V are all out of range . Granted motherboard monitors (especially on consumer boards of that vintage) are not always reliable, so testing with a multimeter while the system is running (careful not to accidentally short something) is a good idea .
I tried replacing the CMOS battery with one from the original motherboard of the same model that came with the prebuilt-PC (got a exact replacement that's currently installed due to the original one going bad) and it didn't work.
How do I tone down the volts?
The battery from another board of this vintage will probably also be dead (unless it was changed less than 10 or so years ago). I don't believe it is causing the shutdown issue, but wanted to point that out as as something to eventually address.
As for the PSU voltages, first you should consider measuring them with something you can trust, like a multimeter. Then, if actually needed (multimeter confirms that voltages are off), you can consider what to do. Some PSUs apparently have trimpots to adjust voltage. Even if yours does, that does not mean you should try adjusting anything, as
a) if you don't know what you are doing, you could be risking your life
b) you may not be able to get a given rail into spec without affecting others
c) your current setup might not be loading the PSU enough for it to regulate its outputs properly
d) A measured average DC voltage does not tell the whole story. The PSU could be generating extreme ripple due to crappy design and/or degraded capacitors while still appearing mostly in-spec to a garden variety non RMS multimeter . Such issues can cause instability and damage hardware.
Please share the brand and model number of the supply. It may turn out to be worth testing and possibly having it refurbished, or it may be pointless.
Also, please share clear photos of the motherboard, or at least visually inspect the capacitors for signs of bulging and/or leakage. This can also cause instabilities.