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PSU showing low voltage in HWMonitor

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December 13, 2010 6:39:36 PM

I realize HWMonitor sucks for reading voltages, but I don't understand why it's suddenly reading lower voltages than it did 6+ months ago. When I first used HWMonitor, I'm positive it was showing higher voltages, nearly identical to what the BIOS displays. Here's what the BIOS showed a few minutes ago:

Vcore = 1.38V
3.3 Volts = 3.32V
5 Volts = 5.02V
12 Volts = 12.30V

And here's HWMonitor just now:



The reason I ask is because last week I had 3 reboots under load, and 1 freeze under load. First time it's done this since replacing the RAM a year ago.

AMD Athlon 5600 x2 Windsor
ASUS M2N-SLI Deluxe
G.Skill 4GB DDR2 memory F2-6400CL5D-4GBPQ
Antec True Power Trio 550W
XFX 7600GS 256MB video
*No overclocking*



More about : psu showing low voltage hwmonitor

a c 1204 ) Power supply
December 13, 2010 7:26:40 PM

If your power supply's +12 Volt rail drops below +11.4 Volts or the +5 Volt rail drops below +4.75 Volts under load you've got a power supply voltage regulation problem.

Is your HWMonitor readings that you've posted with the system under load or at idle?
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December 13, 2010 7:51:05 PM

ko888 said:
If your power supply's +12 Volt rail drops below +11.4 Volts or the +5 Volt rail drops below +4.75 Volts under load you've got a power supply voltage regulation problem.

Is your HWMonitor readings that you've posted with the system under load or at idle?



The HW Monitor readings were taken more or less at idle. As to the 12V reading, I'm positive this used to read 12.3 or 12.4 in HW Monitor - i.e. similar to the readings I pulled from the BIOS.

Would you believe HW Monitor that the PSU might be going bad, or believe the voltages I pulled from the BIOS? I haven't tried using a multimeter yet, not sure how to do it with a computer motherboard.
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a c 289 ) Power supply
December 13, 2010 8:15:52 PM

12.3V in bios is a bit towards the high side but still acceptable, i would always trust BIOS readings over software readings. The voltage measuring chips are not consistent between boards and its not well documented what each board uses so the software tends to take a guess and hope to come out close.

To make sure you are accurate use a digital multimeter, i would probe a molex connector, yellow to black will give you 12V.
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a c 148 ) Power supply
December 13, 2010 8:28:27 PM

Might try OCCT which graphs voltage for 60 minutes over a variety of tests (CPU, GPU, etc) . If your PSU is "low grade", be advised ..... the OCCT "PSU Test" has been known to kill off marginal PSU's.
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December 13, 2010 8:49:53 PM

Is there anything that can be done (in the BIOS) about the 12.3V reading? I wasn't sure if that can be adjusted or not.

I put a multimeter across a molex connector as you suggested. 12.15V solid for ten minutes.
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a c 1204 ) Power supply
December 13, 2010 8:57:17 PM

The voltages displayed in the BIOS/CMOS Setup Utility is informational only. It was never meant to be adjustable so there's really no way to calibrate the BIOS voltages displayed to match those that your multimeter shows.
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December 13, 2010 9:27:05 PM

Just as info, there's a fan inside the tower (probably the CPU fan) that likes to throttle up and down -- just enough to annoy anybody using the computer. It does this for about 5 seconds at a time.

Per HW Monitor over the last few hours, the CPU temps have fluctuated 38-46C for core 0, and 39-49C for core 1. They both average about 41-43C. The fan throttling up and down has no correlation to CPU temps or workload. Sometimes happens when the computer is cold, other times when warm. AMD Cool-n-Quiet is disabled in the BIOS.

Also, is it normal for the PSU case to be noticeably warmer/cooler to the touch? Sometimes it's just barely luke warm, other times it's as hot as the motherboard heat pipe.


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a c 1204 ) Power supply
December 13, 2010 9:39:20 PM

The noise could be from a case fan. If it has the cheap case fans that use brass sleeve bearings, the lubricant has probably all evaporated. Try finding the offending fan, clean it and lubricate the bearing.

When was the last time you blew the dust out of the case?
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December 14, 2010 9:24:01 AM

The case is kept clean. It has a dust filter on the front panel that I wash regularly.
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a b ) Power supply
December 14, 2010 12:46:38 PM

Need to take two readings on PSU. First one @ idle, The 2nd one with a Heavy load on the +12 V. A drop of more than 0.4 V indicates poor regulation and/ or dieing PSU. While the low spec for the +12 V is 11.4 V, I normally ditch the PSU if it dropps below 11.6 V. I normally run Furmark (in a window) or Prime 95 to load the +12 V. For High end GPUs furmark will load +12 V more than Prime 95.

Voltage noted in bios are reasonably accurate, But Very low load on +12 V.
Normally you can tell if HDMonitor is not correct because the readings will be considerably off. If you have not changed the version of HWMonitor and it was correct, then dropped that would indicate a drop in the real voltage. I normally verify the displayed reading with a Voltmeter (you indicated you measured it with a DVM @ molex, Do this while running Prime 95 and HDMonitor, complare the readings.
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December 14, 2010 12:52:34 PM

Just something worth noting people, I just ran HW Monitor and it said my 12v rail was under 11v, 10.98 according to HW. In Everest it was 12.10, I'm pretty sure HW is wrong because my system would be down at that voltage.
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a b ) Power supply
December 14, 2010 2:06:43 PM

Yes, Was that under load, or idle.
CPU might function as this goes thru a VR(s) that knock it down to vcore BUT would stress the VRs, GPU is questionable along with HDDs. While the spec is For the +12 v is +/- 5 %, many circuits will operate with a +/- 10 % (the extra 5 % is a margin - But that does depend on the circuit and other factors).

Would verify with a voltmeter (Orange wire to black on molex).

Added +12 V as this is not true for the +5 V if it is used to power TTL logic circuits which is set to 4.75->5.25V, However cmos circuits may work at 4.5 V.
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a b ) Power supply
December 15, 2010 6:29:16 AM

What is the brand and model of psu? that may help us determine if it is going bad, cheaper brands are more likely to go bad.

also you must remember the program measures from points on the motherboard, not the psu. could be bad caps on the motherboard
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January 2, 2011 4:53:01 PM

Update:
I swapped out the existing power supply (Antec TruePower Trio 550W) with a brand new PC Power & Cooling Silencer 370W. I had purchased the latter for a HTPC and forgot I had it.

Almost everything is the same, except the random reboots are gone. That's good news. HWMonitor is reporting virtually the same (low) voltages, so there's proof the software sucks.

I'm scratching my head about a new problem though. When the computer is under a load, and I attempt to use Google Earth, it is substantially more sluggish than before. I'll have Thunderbird open, sometimes 10-15 instances of Firefox, several folders, Adobe Photoshop, Adobe InDesign, open simultaneously. With the old PSU I could run Google Earth with no drop in performance. Now, I need to close programs or folders out before it behaves properly again.

It's worth noting that OTHER programs are not affected when Google Earth is run under these circumstances.

Am I simply maxing out the PSU?
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