Power problems - unstable rails

[Tigger]

Hi, I have just built a new PC and it seems to be running reliably, but the 5V, -5V and -12V rails are being reported as fluctuating wildly in Sisoft sandra and PC Wizard 2006.

The +/-5V rails are reporting as fluctuating from 2V through to 6V, and the -12V seems to fluctuate from -4V to -12V.

Prime 95 torture test ran stably for 2 hours, and everything seems to work reliably. What is going on?

Socket 939 Athlon 64 3200+
Gigabyte GA-K8N Ultra 9
2GB corsair value select ram
Geforce 6800 GS PCI-E graphics
Pioneer DVD RW
DVD ROM
Hitachi deskstar 250GB HD
120 GB IDE HD
40 GB IDE HD
Seasonic 500w power supply

Tigger

[arthurleung]

-5 and -12V rail doesn't matter. If your +5V rail really fluctuating badly thats what you need to worry about.

Your Seasonic should push the above with ease

[aidanjt]

Hi, I have just built a new PC and it seems to be running reliably, but the 5V, -5V and -12V rails are being reported as fluctuating wildly in Sisoft sandra and PC Wizard 2006.

The +/-5V rails are reporting as fluctuating from 2V through to 6V, and the -12V seems to fluctuate from -4V to -12V.

Prime 95 torture test ran stably for 2 hours, and everything seems to work reliably. What is going on?

Faulty voltage sensors, use a real multimeter to test your rails.. that kind of wild voltage fluxuation would destabalised your computer.

[herulach]

Its possible that your power supply doesnt actually have a -12V rail, hence why the readings are waky

[Tigger]

Thanks for the info, I wouldn't know where to start to find the different rails with a voltmeter and to be honest I don't fancy blowing the motherboard by randomly stabbing voltmeter probes on to components. I have an old generic 400W PSU which I was going to try to see if the same results occur.

Can anyone suggest other software to monitor the voltages in case the conversion factors in Sisoft sandra and PC Wizzard are incorrect? How can I tell what system health chip I have and what it is capable of measuring? I have the gigabyte easytune 5 software which came with the motherboard, and the system health part of that program only monitors Vcore, +3.3, and +12 which are all rock solid. Wouldn't they have included the other voltages (+5, -5, -12 and standby) if the chip could monitor them, as these are the ones which other software reports as fluctuating?

Tigger

Socket 939 Athlon 64 3200+
Gigabyte GA-K8N Ultra 9
2GB corsair value select ram
Geforce 6800 GS PCI-E graphics
Pioneer DVD RW
DVD ROM
Hitachi deskstar 250GB HD
120 GB IDE HD
40 GB IDE HD
Seasonic 500w power supply

[herulach]

Dont worry about -5 and -12, they arent used, as i said, your psu prob doesnt have them.

To test the 5V rail you can just put a multimeter across the red and black connectors on any molex.