I was curious this morning about my temperature and voltage readings so I downloaded Speedfan and CPUID's Hardware Monitor.

I have the following hardware

CPU : i5 3.2GHZ

RAM : 4 x 2GB DDR3

GPU : HD 5770 Hawk

HDD : 3 x 7200RPM Drives (SATA2)

The first question, The voltage reading on idle on my 12V rail is sitting at 8V and I've read somewhere that due to windows 7's power management that under idle, the voltage would drop, is that correct?

The second question, My CPU Core is at 42Degrees C, which is fine and i'm happy with it, but my SYSTIN temperature reading is sitting at 100 Degrees, which I cannot believe to be true. Might there be a problem with the earlier DH55C motherboard sensors?

I have not checked what those readings are under load, but I will check tonight. I just want to know whether you folk think that 550W is enough and if these readings are acceptable?


  • It is very unlikely that your system is working at all if the "12V" is only at 8 volts. Before you do anything else, get a voltage reading you can trust. A LOT of mobo voltage and temp sensors give wrong results. Buy a cheap digital multimeter (e.g. ExTech MN35 or similar... there are cheaper ones, but that's about the cheapest I'd recommend... borrow one from a techie friend if you have to) and measure the voltage at an unused 4-pin "Molex" connector from the PSU. Or "back-probe" the motherboard connectors. The wires with black insulation are ground, yellow for +12, red for +5. – Jamie Hanrahan Mar 29 '18 at 21:54
  • Oh, and: No, the voltage will not drop due to power management. The system has no way whatsoever to tell the PSU to lower its voltage. Power management causes the system to use less power but that is not done by lowering voltage. – Jamie Hanrahan Mar 29 '18 at 21:56
  1. A 33% voltage drop on a rail is too high and indicates that either the PSU is faulty or that the load is too high. And load drops when idle, raising the rail rather than lowering it.

  2. That is definitely too high. There may be a fault with the motherboard causing voltage to be converted to heat (and thereby causing the aforementioned rail drop), or it's struggling to compensate for the rail drop caused by the PSU.

There is something severely wrong with your system, and I urge you to take diagnostic and corrective action as soon as possible.

  • 1
    a 8V voltage in the 12V rail is unlikely to give anything past a POST screen, much less likely a windows interactive session... – bubu Apr 29 '11 at 6:21
  • Thank you for your answer, do you really think that there might not be something just fishy with the sensors? Can you recommend any diagnostics that I can run (software related) that will pin point an issue if there is one? – PieterG Apr 29 '11 at 6:22
  • Perhaps. I had gone with the assumption that you had tested the rail with a multimeter, and not just gone by what the sensors reported. But sensors this faulty would be a problem with the motherboard regardless. I would not trust software diagnostics at this point, since they would all rely on what the sensors report. – Ignacio Vazquez-Abrams Apr 29 '11 at 6:25
  • I will ask the supplier if I can swap out the motherboard then? – PieterG Apr 29 '11 at 6:35
  • The first thing I would do is check that rail, since if it really is that low then a motherboard change won't help. Once you've verified that the rail is fine, then change the motherboard. – Ignacio Vazquez-Abrams Apr 29 '11 at 6:38
  1. It is not the 12V rail being 8V - it is the sensors having problem. You implied in your question that you were able to boot windows 7. In no[1] way would a machine be able to boot with 12V rail at 8V. If anything, the motherboard needs to be changed. Almost any respectable PSU would have undervoltage protection which shutdown the system the moment the voltage runs out of specification.

  2. Given (1), I think it is likely that the sensors are having problem. In rare instances of water cooling with no channeled air towards the chipset and voltage regulators it may be possible to heat the 'system' area so badly that you have such reading but I don't think its the case here. :)

  • BTW, Use a multimeter... – bubu Apr 29 '11 at 6:19

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