BIOS shows 12V @ ~10.5 - is that too low?

[TheDarkKnight]

My computer has been shutting down randomly and sometimes won't boot back up until it has sat awhile. I am "thinking" the power supply is approaching its last days. The system is about 5+ years old now so it's done its job.

But what I am confused about, is that in the BIOS the voltage shown on the 12V is ~10.5. But when I tested the 12V with my digital multi-meter through a standard 4-pin molex connector on the power supply, I got a reading of 11.6 volts. I have heard something about power supplies coming with 2 12V rails. So, are these different numbers that I am seeing because they are on two different 12V rail voltages? Is it possible that only 1 12V rail is bad and not the other? How do I test both 12V rails other than grabbing a random 4-pin molex connector?

P.S. The 5V rail tested ~5+ so that one seems okay.

Thanks for any/all comments.

 

[Z15CAM]

If you are experiencing low voltage suggest you clean and reseat both the PSU and MB interface connectors and see if that corrects the issue - If not RMA your PSU.

NO matter how much I criticize FanSpeed the app does report accurate Voltages in respect to your MB Bios.

 

[TheDarkKnight]

If you are experiencing low voltage suggest you clean and reseat both the PSU and MB interface connectors and see if that corrects the issue - If not RMA your PSU.

NO matter how much I criticize FanSpeed the app does report accurate Voltages in respect to your MB Bios.

The power supply is about 5 years old. I don't think I can't get an RMA now. I did disconnect a second/slave hard disk drive and my optical CD/DVD drive to see if the system would boot then. It appears to be working better with a lighter load but not sure for how long.

But what about the 10.5 voltage reporting in my BIOS for a 12V requirement. Is that acceptable?

 

[tortillasoup]

Dude, your PSU is toast, get a new one. I know you're just posting here looking for confirmation and this is that post giving you confirmation that the PSU is bad/dead.

 

[Torn Mind]

ATX spec allows for a 5% deviation above and below 12v. That is, if the voltage reading is about 12.6 or 11.4 volts, the PSU is not functioning properly.

It is possible that going into BIOS loads the CPU fully, thus pulling more current from the 12v rail. You might be able to replicate the behavior by running a CPU stress test in your OS and taking multimeter readings that way. 11.6 volts on idle is cutting it pretty close, if your multimeter readings are when all components are idling.

 

[dave_the_nerd]

But what about the 10.5 voltage reporting in my BIOS for a 12V requirement. Is that acceptable?

nope.

 

[TheDarkKnight]

Dude, your PSU is toast, get a new one. I know you're just posting here looking for confirmation and this is that post giving you confirmation that the PSU is bad/dead.

Is it safe to say that dead could be defined as 'showing no signs of life'? By that definition I wouldn't say that it's dead.

Now describing it as bad would probably be more accurate.

Yes, I was looking for confirmation because I am not highly educated in the area of power supplies so I needed the confirmation.

10.5 volt reading on a 12V spec in the BIOS equals bad. Okay.

Thanks to everybody and tortillasoup for the help.

 

[philipma1957]

Is it safe to say that dead could be defined as 'showing no signs of life'? By that definition I wouldn't say that it's dead.

Now describing it as bad would probably be more accurate.

Yes, I was looking for confirmation because I am not highly educated in the area of power supplies so I needed the confirmation.

10.5 volt reading on a 12V spec in the BIOS equals bad. Okay.

Thanks to everybody and tortillasoup for the help.

what was your psu model and company. many good psu deals around.

was it a modular or fixed cable? was it 450 watts 500 watts 650 watts?

 

[bryanl]

I've seen BIOSes report voltage values that could not possibly be correct, for the simple fact that nothing would be visible on the monitor if those values were real. A multimeter is the only trustworthy method of verifying voltages.

When a power supply has multiple 12V rails, typically one rail powers the motherboard, and the other rail powers the peripherals through the IDE or SATA connectors.

 

[SparkyJJO]

Let's put it simple

Never trust the BIOS voltage readings. I don't know why they can't put some half decent voltage sense circuitry on a $100 motherboard when a $5 meter can read it accurately, but whatever. 10.5V would not even power up your PC, so you know the BIOS is a lie there.

That said, 11.6 at idle measured with a DMM is still quite low, borderline. So get any sort of load on the 12V rail and I could see it dipping down a bit more and crashing the system.

What power supply is it by the way?

A way you can test the rail feeding the motherboard is to simply stick the red probe in the back of the 24 pin or 4/8 pin connectors on the motherboard of the wire you want to check. Easy to get the probe to make contact there.

 

[Liquid_Static]

11.6 is not okay, let alone 10.5. RMA that shiz.