High +12v rail

  Pamy 16:12 14 Feb 09

Hello everyone,
for the last two days my computer has been shutting down and starting up on its own, (up to 8times today). I have looked through the events log but without finding anything. I have installed a program called "Speedfan" to monitor temperatures, fan speeds and voltages, it shows that the +12v is actually 13.01v to 13.4v.
This seems too high to me and may be the cause of the shutdowns and restarts. Is it possible to reduce the voltage via software, or is this a fault with the Power supply?

  Fruit Bat /\0/\ 16:22 14 Feb 09

Fault with power supply

  Pamy 16:28 14 Feb 09

Hi Fruit Bat /\0/\, what do you think the max votage should be?

  caccy 16:40 14 Feb 09

Spec for +12V is +11.4V to +12.6V
Check out the specification on "click here"
As Fruit Bat /\0/\ says, Power Su[pply U/S. However check it first using a multimeter just to make sure.

  DieSse 16:41 14 Feb 09

This intel document on PSU design gives guidelines for voltage tolerances.

click here\specs\ATX12V_1_3dg.pdf

The +12 should be ± 5% - up to ± 10% is allowed under full load.

It would indicate that 13.4 is too high. However - it may be worth checking in the BIOS too, as it may be that Speedfan is not entirely correct (not that I have any knowledge that it could be.)

  Pamy 16:56 14 Feb 09

thanks caccy, and DieSse,
DieSse, your link did not work for me. So if the power supply is out of spec. would you agree with me that that is the cause of my problem, or could it be something else?

  Fruit Bat /\0/\ 16:59 14 Feb 09

Dying PSU would give the symptoms you describe

  Pamy 17:03 14 Feb 09

Hi Fruit Bat /\0/\, yes that is what I think but just wanted to get as much confirmation as posible before commiting another wad of pensioner notes to this other oldie.

  DieSse 20:27 14 Feb 09

"....would you agree with me that that is the cause of my problem"

It may be - the circuits which monitor power supply voltage may actually be doing the shutdown.

You should replace it as a first step, anyway.

  T0SH 22:29 14 Feb 09

The 12 volt line on an ATX power supply is only used to supply drive rotation motors and cooling fans neither of which would suffer any particular hardship with the variance indicated

Have you checked in the event viewer to see if that gives any indication of faults occurring at or about the times of your restarts ?

also try turning off "Automatically Restart" in the system properties startup and recovery settings section, doing this will bring up a blue screen error indicating a faulting module which can help with diagnostics

Cheers HC

  ton 22:53 14 Feb 09

I wouldn't take much notice of Speedfan readings.

I just looked at it and it shows one of my 12v lines at 16.8v, and a 5v at 6.85v.

I don't have any problems with the PC so I ignore what Speedfan says.

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