Odd Reading on the +12V Rail


I noticed that Speedfan reads the +12V rail as 4.75 to about 5 V while on idle. On full load (during stress test) it jumps back to normal 11.89 to about 12.49 V. Got the same exact readings on CPUID Hardware Monitor and Everest.

I have tried two power supplies, Kingwin LZG-1000 and Sparkle 1000 W, and the results are the same.

If both power supplies are functioning correctly, then could it be my motherboard on the 20+4 pin or the 8 pin EPS?
6 answers Last reply
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  1. Hello Admiral_Cecil;

    Those software utility programs are semi-notorious in reporting inaccurate voltages.
    Does your MB BIOS or motherboard utility software show the same values?

    The 12V allowable spec range is plus or minus 5 percent (min 11.4 / max 12.6).
  2. I wouldn't trust Speedfan, if your system is stable then nothing should be wrong.
    Software readings (Especially speedfan) do sometimes give inaccurate readouts, try using a multimeter if you really want to find out the voltages.
  3. Hello,

    Yes, the bios is reading all the rails +3, +5, and +12V within the +/- 5% as you mentioned.
  4. I'd put my trust in the BIOS readings.
    Since you've tested two PSUs and got the same results I think you're in good shape.
  5. K, thanks for the tip.
  6. your computer wouldnt boot if there were 5v on the 12v rail. but anyhow many software monitoring programd (esp speedfan are unreliable)
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