Hi Brett, First off, CMOS checksum errors during boot refer to MEMORY not the BIOS. Also almost all your symptoms point to a possible memory issue. Do Chuck's stuff to verify that you don't have a power drain that's causing a memory issue. Get a Memory Test utility and find out which DIMM is causing the problem. Carefully remove the DIMM and using a #2 pencil eraser, clean the contacts and replace the DIMM (The rubber removes oxidation that prevents contact) and don't forget to keep grounded! (You, not the DIMM). Cheers Karl On Sun, Sep 30, 2012 at 12:00 PM, <wlug-request@mail.wlug.org> wrote:

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Today's Topics:

1. help diagnosing PC issue: suspect power supply (Brett Russ) 2. Re: help diagnosing PC issue: suspect power supply (Chuck Anderson)

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Message: 1 Date: Sat, 29 Sep 2012 14:32:05 -0400 From: Brett Russ <bruss@alum.wpi.edu> Subject: [Wlug] help diagnosing PC issue: suspect power supply To: Worcester Linux Users Group <wlug@mail.wlug.org> Message-ID: <CAGcHgFNRd2jLrywD977a0jZChqEREnNBt529abY0= fh2OU5FAA@mail.gmail.com> Content-Type: text/plain; charset="iso-8859-1"

Hi,

I'm trying to diagnose a home built PC running fine since 2007 but lately starting to act odd. Here are the system specs: Intel Core 2 Duo 1.8GHz cpu Asus P5B Deluxe mobo Nvidia 7900GS graphics card Kingston KHX6400 2x1GB DDR2 memory Sparkle ATX 400W power supply 3x 1TB SATA HDDs 1x SATA DVD-RW

$ uname -a Linux spider 3.0.0-25-generic #41-Ubuntu SMP Mon Aug 13 17:58:59 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

$ cat /etc/*release DISTRIB_ID=Ubuntu DISTRIB_RELEASE=11.10 DISTRIB_CODENAME=oneiric DISTRIB_DESCRIPTION="Ubuntu 11.10"

$ uname -a Linux spider 3.0.0-25-generic #41-Ubuntu SMP Mon Aug 13 17:58:59 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

What recently changed:

i) replaced monitor, last one died

ii) (carefully) vacuumed the dust from inside. Kept hand on case chassis, didn't touch any PCB/chips, etc.

Here are the symptoms:

1) first started seeing BIOS claims of bad CMOS checksum at boot time. Immediately suspected the CMOS battery, replaced it and reset CMOS settings but I continue to see this. This is the one symptom that I can't yet place, unless it's simply a bad replacement battery.

2) next started seeing the monitor fail to wake up after entering power save

3) powering on the PC shows issues:

3a) often the monitor won't wake at boot

3b) the bios often doesn't finish POST, gets stuck at splash screen

3c) bios settings often don't survive across power cycles (possibly related to #1--battery issue?)

3d) bios doesn't always give the affirmative beep (likely same symptom as 3a, 3b)

3e) a cold power on or reset can take several "tries" before the system stays on. I.e. fans will spin up, then spin down, one to three times before staying on. When this happens it's pretty much guaranteed that it won't boot successfully.

4) system will freeze to user input while up. I.e. once I get Linux booted, as long as I disable monitor power save it will stay running for a while, but I observed it stopped responding to KB and mouse input earlier this morning.

Here's what I've tried:

a) reseated both DIMMs, reproduced issues; tried with just one DIMM, repro'd; tried other DIMM, repro'd

b) reseated graphics card, repro'd; removed graphics card (now headless), repro'd problem 3e

c) reseated CMOS battery (CR2032), repro'd

d) pulled all non-essential cables and internal connections, including power and SATA cables from all drives, repro'd

e) updated BIOS to latest version, repro'd

Unfortunately I don't have another ATX power supply to try, but was thinking of buying one. I might also try an old PCI video card, but I suspect due to repro (b) above that it's not the cause.

Anyone have any other insights or agree it sounds like a bad PS? I still can't explain symptom (1), will probably buy another battery to be sure. Five years seems like an old PC, but I'm not a gamer so this suits me fine.

Thanks, Brett -------------- next part -------------- An HTML attachment was scrubbed... URL: http://mail.wlug.org/pipermail/wlug/attachments/20120929/8959d06a/attachment...

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Message: 2 Date: Sat, 29 Sep 2012 18:19:47 -0400 From: Chuck Anderson <cra@WPI.EDU> Subject: Re: [Wlug] help diagnosing PC issue: suspect power supply To: Worcester Linux Users Group <wlug@mail.wlug.org> Message-ID: <20120929221947.GH12327@angus.ind.WPI.EDU> Content-Type: text/plain; charset=us-ascii

On Sat, Sep 29, 2012 at 02:32:05PM -0400, Brett Russ wrote:

...

Sparkle ATX 400W power supply Anyone have any other insights or agree it sounds like a bad PS? I still can't explain symptom (1), will probably buy another battery to be sure. Five years seems like an old PC, but I'm not a gamer so this suits me fine.

I agree that the power supply is suspect. You can measure the voltage on a spare power supply hard drive connector, there should be 12v from black to yellow, and 5v from black to red. If that checks out, you should measure from the motherboard ATX connector as some of the other voltages may be out of spec. You can find the standard ATX pinouts and voltages online. Finally, you can test with the power supply completely disconnected from the PC. Again, you can find instructions online for how to do that, as it requires a jumper wire for the power supply to power on.

Alternatively, it may be easier to just try a replacement.

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End of Wlug Digest, Vol 107, Issue 13 *************************************