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I have converted two ATX PC power supplies to 12V bench power. They have worked flawlessly for the past 5 years. Suddenly, both are providing 17V+. What could be causing this? I have a 10ohm resister connected between the 5V and ground. Should I put this on the 12V as well? The 5V rail produces the most current as they are both old power supplies.

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    \$\begingroup\$ Are you sure that resistor is still good? A 10 Ohm resistor on 5V dissipates 2.5 Watts, that's much more than a standard resistor can handle. \$\endgroup\$
    – PMF
    Commented Sep 23, 2022 at 16:03
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    \$\begingroup\$ Have you measured them in the past and found 12V at no-load? \$\endgroup\$
    – vir
    Commented Sep 23, 2022 at 16:07
  • \$\begingroup\$ Just tried a new resistor....no change. Also measured the voltage in the past no load and it was around 14v \$\endgroup\$
    – shaggy_sb5
    Commented Sep 23, 2022 at 17:27
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    \$\begingroup\$ If your multimeter measures 17V on both supplies, change multimeter batteries. \$\endgroup\$
    – Justme
    Commented Sep 23, 2022 at 17:27
  • \$\begingroup\$ what do the other outputs measure? \$\endgroup\$
    – jsotola
    Commented Sep 23, 2022 at 18:08

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