High -12V on Tagan 480W PSU

The -12V rail on my new PSU is surpising high, 12.610V while idling, and has been above (or below...) -12.7V. Any what causes this or what the problems this could give? And is this a manufactuers fault? There is not a high load on the PSU, only an Althon XP, 512mg of ram, 1 HDD, and a geforce 6800GT.

It's worring that i have only seen this now, because i ordered this along with a load of parts for a complete system and I had numerous problems while setting it up, corrupted XP install, BSOD's, freezes at the POST screen. I tested it with new memory, new video card, new HDD and none made a difference so I sent back the CPU and motherboard yesterday and assembled the remaining parts along with the parts from my old PC and i got warning messages from my monitoring software about the voltage levels as soon as i opened a game.

What are your other voltages like?

My -12V is at about -8V but it isn't a problem. -12V is something of a legacy thing, used as part of the signalling in RS232 connections (eg serial ports.) That is, of course, unless it has other uses I don't know about...

Suffice to say, if mine is low and I have no problems, yours being a tad high shouldn't cause any issues.

Have you got that 6800GT on it's own cable? I.e. not shared with anything else on the same branch from the PSU? (I'm assuming the GT is a single molex card - if it's two molex then they should be from different branches of the PSU and if possible still keep them clear of any other devices). Also an XP + GT is not what I'd call a low load - your PSU could well be suffering though 480W SHOULD be enough.

Try Motherboard monitor (Google for MBM5) to monitor voltages and Prime 95's torture test (www.mersenne.org) and see how much your vcore, +3.3V, +5V and +12V lines fluctuate under load. Presume you aren't overclocking (anything - including lowering the RAM timings)... If so test at stock first. Also IIRC the -12V line isn't important and can be +/- 10% (1.2V) out and still be considered in spec.

multi meter ,thats the only accurate way of testing the voltages m8

treat what the monitoring software says as a rough reading not an accurate 1

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Originally Posted by da_ging

multi meter ,thats the only accurate way of testing the voltages m8

treat what the monitoring software says as a rough reading not an accurate 1

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Agreed - but I'd add a proviso - depends on what you're using it to measure... You can easly tell how well the PSU is doing (and eliminate and doubts about it) but not how well the mobo is doing - i.e. how / where do you measure vcore? The readings given by the mobo might be accurate even if the PSU is spot on - the mobo might still be pap at regulating what the PSU is supplying...

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Originally Posted by Kez

What are your other voltages like?

My -12V is at about -8V but it isn't a problem. -12V is something of a legacy thing, used as part of the signalling in RS232 connections (eg serial ports.) That is, of course, unless it has other uses I don't know about...

Suffice to say, if mine is low and I have no problems, yours being a tad high shouldn't cause any issues.

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Glad to hear that :)

My other voltages are,

+5V: 4.972V
+12V: 12.099
-5V: -5.149
5VSB: 4.872

The 6800GT has one molex connector and is using its own connector and not sharing with other devices.

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Originally Posted by malfunction

Also an XP + GT is not what I'd call a low load - your PSU could well be suffering though 480W SHOULD be enough.

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Well, I will be running Althon64, 1gb of RAM, bigger HDD, and the 6800GT on it when i get the parts back from OcUK (working this time i hope!).

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Originally Posted by Mblaster

My other voltages are,

+5V: 4.972V
+12V: 12.099
-5V: -5.149
5VSB: 4.872

The 6800GT has one molex connector and is using its own connector and not sharing with other devices.

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Your +5V and +12V are spot on - nothing to worry about at all... I don't think -5V's important and +5V SB (standby) is only used for... when the PC's in standby ...so no worries on that either. What about +3.3V?

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Originally Posted by Mblaster

Well, I will be running Althon64, 1gb of RAM, bigger HDD, and the 6800GT on it when i get the parts back from OcUK (working this time i hope!).

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Put it through Memtest86 and Prime 95 torture testing when you get it back - make sure it's not duff.

The 3.3V is fine although MBM reports it as 2.7V! (my memory voltage) I tested with a multimeter.