I’ve got a ton of older computers I’m working on, and on almost all of them the -12v shows 12.0v or 12.1v (tested using a PSU tester, NOT SOFTWARE)
However, on some of them, it reads 11.7, or as low as 11.1 if I load it with hard drives.
How bad is too bad? I’m fairly comfortable with 11.7, but I don’t know about 11.1.
ATX rev. 2.52 has 12V at ± 5% for a min of 11.4V and a max of 12.6V. I would not be using a power supply that falls anywhere outside of that range.
I appreciate that info, thanks! I did try to google the ATX spec myself before I posted that question here, but I was having a hard time finding the actual voltage specs, I just kept finding pinouts and other general guidelines.
Thank you!
I have some of these types of things bookmarked so I can get to them quick 
Intel has the rev. 2.52 guidelines available in a PDF:
They’re good to keep handy.
I actually just saw you were talking about the 12v earlier, I was talking about the -12v, which according to the picture can go as low as -10.8v
I still think -11.1 is way too low, so I’ll just dump any old PSUs that get below -11.4 and call it safe, no need to use them when replacements are cheap and plentiful
Reading the fucking docs 
Is required for an engineer
You then have the read the specs of the MB and CPU causing problems etc. One component could be out of ATX power supply spec and not compatible.
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