power supply problem

[rlaycock]

Hi
Occasionally when I start up my computer which has a Thermaltake pure power 480w psu the computes fails to boot reporting that hardware monitor found an error.... I have traced it to the 3.3 v rail (red in bios and only reporting 2.9 v, when it goes above 3 v it goes the correct color in bios). When the computer is running it reports about 3.24v sometimes dropping a little lower but hardly ever below 3.2vI am using ASUS pc probe to monitor the voltage whilst it is running. The motherboard is a asus p4pe and cpu 2.53 p4.
This problem started about 2 or 3 weeks ago I have not changed any hardware and the machine is running fine. The fail to boot is only occasional Is my power supply failing and should I return it. Or do you think I could safely ignore the odd time it fails to boot .
Thanks if you can help
Bob

 

[FlyingPenguin]

Not something I'd ignore. It's not right, and it might eventually get worse.

First of all the onboard voltage monitoring is notoriously unreliable. The only accurate way to measure voltages is with a digital multimeter.

That said, you may have a bad PSU or you may have a problem with the mobo. Do you have another PSU you can temporarily install to see if that fixes the problem (no need to phyically install it, just wire it in)?

Check you mobo for bad capacitors. Some photos of what to look for here: http://www.pcstats.com/articleview.cfm?articleID=195

Hope this helps...

 

[deathwalker]

You have insufficient evidence to show that the Power supply if failing!! Penguin is accurate in his statement that bios power monitoring is unreliable and at those low voltages you should not take what it reports to you to the bank.!!

 

[rlaycock]

Thanks for the help folks.
I was watching it closely last night and recording the history with pc probe and apart from the occasional boot error message the 3.3 does look reasonably stable when operating. Readings of 3.248v and 3.234v and occasionally just under 3.2v. This was changing the load by playing games etc. Don?t know if that makes a difference? It seams as though it only goes into the red zone (below 3v) on the occasional cold boot which it has done 3 or 4 times over the last 3 weeks. Is this a clue?
I Think as it appears to be reasonable stable when it is running I will continue to monitor it closely and I will have a close look at the capacitors but unfortunately I don?t have a multy meter or a spare psu to try. If the problem seams to be worsening I will bye a new psu and try that. Does that sound like a good plan?
Thanks again
Bob

 

[rlaycock]

Hi all
I managed to borrow a multi meter and tested the rails, the 3.3v rail is steady at 3.44 (asus pc probe reporting 3.23!!!) also checked the 5v rail =5.25 and the 12v rail =12.16all very steady so I guess it is not the psu and my motherboard monitor must not be reading correctly.
Any idea why the motherboard monitor would start to read inaccurately?
Any suggestions of how to fix it?
Do you think I am safe to ignore the low motherboard monitor readings?
Thanks if you can help
Bob

 

[mountcarlmore]

mbm5 cannot possibly report the correct voltages, because the readings that it gets is from the mobo, not even the psu. you are deeply mistaken if you think the voltages your mobo reports, maybe even correctly, are the same as the psu puts out. its physics, voltages change as they hit resistance on the mobo, all the capacitors, and other crap. the voltages that the sensor chip gets arent even important as theyare not nearly as well filtered as the voltages your video card or memory gets.

 

[FlyingPenguin]

If it is a PSU problem, it's not uncommon for voltages to be unstable during boot and smooth out the rest of the time. Booting a computer puts a lot of stess on many components, including the PSU.

For example I had a bad PSU in my main workstation 8 months ago (bad capacitors in the PSU it turned out - they were leaking). The computer worked fine while it was turned on and it was on 24/7 with a UPS connected to it. However every time I needed to reboot it (because I installed some updated drivers) the PSU would spike the hard drive and damage it. I went through three hard drive RMAs before I figured this out.

It's hard to say in your case. You may have a defective PSU or a defective mobo. It may never get any worse. I used to have an Epox 8RDA+ that would fail to POST 10% of the time. I would turn off the power and turning it on again and it would boot just fine. Never gave me any trouble other than that and since I ran it 24/7 it wasn't much of an issue.

Only way to know for sure if it's the mobo is to swap it out and see what happens. Never hurts to have a spare PSU on the shelf anyway. I can highly recommend the Enermax NoiseTasker 495. Nice PSU for the price. It's usually $85 shipped at Newegg. It's what I have installed in all my rigs.

Check for bulging/leaking caps on the mobo when you get a chance.

Hope this helps...

 

[stevty2889]

There is proably a setting in the bios to disable the monitoring of that rail. The 5v rail on one of my computers(which strangely happens to have a thermaltake PSU as well) was showing as low as 1.8v, but was steady at 5v with a multimeter. I just disabled the monitoring of the rail, and haven't worried about it since, because software monitoring is rarely accurate.