It's alive! (not)

February 6, 2006 7:43 PM

My computer occasionally locks up, and sometimes completely fails to boot when I press the power button. Linux's "sensors" reports out-of-range voltage values.

My system with the below specs, sometimes locks up randomly. This requires a hard reset, and SysRq+R,K,S,U,B doesn't help. Sometimes, it does not turn on at all when I press the power button, and sometimes it turns on, and the fans start spinning, but I get no video. Here are my specs:

Motherboard: Soyo KT 880 Dragon2
They have a version 2.0 of mine, so maybe mine is really bad?
Video Card: NVidia GeForce 6600GT
CPU: AMD AthlonXP 2600+ 1.9 GHz
Power Supply: 400W (or 350W, I can't remember) Athena Power

'sensors' output:

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it87-isa-0290
Adapter: ISA adapter
VCore 1: +1.63 V (min = +1.42 V, max = +1.57 V) ALARM
VCore 2: +3.39 V (min = +2.40 V, max = +2.61 V) ALARM
+3.3V: +5.92 V (min = +3.14 V, max = +3.46 V) ALARM
+5V: +4.97 V (min = +4.76 V, max = +5.24 V)
+12V: +10.05 V (min = +11.39 V, max = +12.61 V) ALARM
-12V: -16.32 V (min = -12.63 V, max = -11.41 V) ALARM
-5V: -5.60 V (min = -5.26 V, max = -4.77 V) ALARM
Stdby: +4.68 V (min = +4.76 V, max = +5.24 V) ALARM
VBat: +0.00 V
fan1: 0 RPM (min = 0 RPM, div = 8)
fan2: 4218 RPM (min = 664 RPM, div = 8)
fan3: 0 RPM (min = 664 RPM, div = 8)
M/B Temp: +34 C (low = +15 C, high = +40 C) sensor = thermistor
CPU Temp: +39 C (low = +15 C, high = +45 C) sensor = thermistor
Temp3: +51 C (low = +15 C, high = +45 C) sensor = thermistor ALARM

---

The voltages stay constant most of the time, and I've seen Temp3 go as low as -9, and as high as 62. It has ALARM next to it maybe 20% of the time...Wehn I boot up after a lock-up, the logs show nothing.

What should I do? Is "sensors" misreporting, or do I need to buy: a) a new power supply, b) a new motherboard, or c) both?

posted by bkudria to computers & internet (6 comments total)

lm_sensors usually needs to be calibrated for your particular motherboard by putting 'compute' values into sensors.conf. Getting ones that are known to be accurate can be a chore. For known good sensor readings, most BIOSes have a page that lists voltages and temperatures. Your motherboard should have one.

If your voltages really aren't that wacky, your power supply still could be bad. Bad power supplies are certainly one of the biggest causes of system instability, behind bad RAM. You can test your ram with memtest86+.

If you do buy a new power supply, get a known good reliable brand like Seasonic or Antec.
posted by zsazsa at 8:03 PM on February 6, 2006

Sounds like a hard problem to diagnose. definitely do memtest.

The out of range voltage says Capacitor Plague or bad power supply, I guess. The board may be a bit modern for a capacitor problem, but you should still check. Even the slightest bulge is a clear indication of a problem - here is a previous question with lots of bad caps talk.

I think the funky temperature readings are an artifact of strange voltage fluctuations. You should still manually confirm that temperatures are reasonable.
posted by Chuckles at 8:29 PM on February 6, 2006

Your VCore 1 value is good, I think. The voltage for your processor is 1.65v. VCore 2 is meaningless. CPU and mobo temps are fine as well, including their max.

Not sure what Temp3 is measuring, and the +/- 3.3v/12v measurements concern me, but I can't back my concerns up with anything definite other than to say that they seem out of wack.

I'd go into BIOS, and check to see that the processor and memory settings are correct. Ensure that the voltages are set properly, including that for your memory (which should be either 2.5 or 2.6v). Also make sure the timings are correct.

Bottom line: if I were in your shoes, and had the same problems, I'd do the whole try-booting-with-various-cards-out routine (which rarely fixed my problems), and then go buy a new power supply (which did once).

Good luck!
posted by herrdoktor at 8:32 PM on February 6, 2006

I imagine feeding 5v to a circuit rated for 3.3v would fry it. As stated above, it's almost a certainty that the data are erroneous.

Manually testing the PSU will provide better results. You'll need a multi-tester and a paper clip. Short the green wire to any black and the unit will turn on. The following page will give you info on what you should find.

http://wiki.ehow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply
posted by kc0dxh at 2:40 AM on February 7, 2006

The fast check is to meter the +5V and +12V lines, which are trivial to reach -- they're the red (+5V) and yellow (+12V) wires in the drive power connectors.

Meter against ground -- handily, the two black wires in a drive power connector are ground. So, set the meter for DC volts, put the black probe into a black socket on a large drive power connector, and put the red probe into the red one. You should see +5V, or +12V. Move the red probe to the yellow wire, you should see the other voltage.

Compare those numbers to the +5 and +12V numbers from sensors. If they're similar, you have a power problem. If sensors is telling you that you only have +10VDC, but your meter is saying +12V, sensors is probably wrong. (Your meter might be wrong, but it's a really sad meter that can't get +12VDC within .2V nowadays.)

Note that testing a power supply with no load can lead you astray -- it may well put out 12.00VDC without a load on it. You don't care about that. You care that it can put out 12VDC with your computer running off it. Indeed, many won't even start without some load -- the trick to making them into bench power supplies is to hang a large power resistor between the +5V bus and ground to put enough load on the supply so that it'll run without other loads connected.
posted by eriko at 3:28 AM on February 7, 2006

Thanks for the feedback, guys! I agree with kc0dxh that these voltage values are erroneous...I'll take eriko's suggestion and manually test it to make sure, and then write down the numbers from my BIOS screen to calibrate it.
I'll also run memtest off my Ubuntu LiveCD, since this seems to be the cause of the lockups.
Thanks for the helpful tips!
posted by bkudria at 5:14 PM on February 8, 2006