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My PC won't boot anymore (not even POST beeps).
I measured the power supply. All voltages are PERFECT except the negative rail. My multi-meter shows -11.2V instead of -12V.

Is this rail necessary for the PC to pass the POST test?
From what I understand the negative rail is only for backward compatibility only....

The power supply is 750W (from Antec). Worked for 11 years.

Gabriel
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    I think the -12V supply only needs to be within +/-10% so 11.2 is fine. The others are +/-5% – Finbarr Dec 22 '22 at 16:12
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    Good chance your PC doesn't even use -12v. – user1850479 Dec 22 '22 at 16:13
  • Yeah, the only thing I know for sure [might use -12V is RS232](https://www.ti.com/lit/an/slla544/slla544.pdf) but many RS232 transceivers generate the required voltages themselves these days to avoid unnecessary power supplies. Vaguely related: [Why is -12V needed on an ATX power supply](https://superuser.com/questions/839107/why-is-12v-needed-on-an-atx-power-supply) and [The purpose of PSU & motherboard -12V line](https://superuser.com/questions/1702506/the-purpose-of-psu-motherboard-12v-line) – Mokubai Dec 22 '22 at 19:30
  • "*I measured the power supply*" -- How? With or without a load? – sawdust Dec 22 '22 at 22:01
  • @sawdust - with mainboard connected and powered on. – Gabriel Dec 27 '22 at 18:15

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