Resolved Power kill, then checksum

While receiving a small group of emails, yesterday, the computer shut down as if I flipped the PSU switch, or unplugged the power cord. Everything went out... even the post LEDs. It had no power at all.

I fooled with it, cleared the CMOS, which I usually do for most problems, even if it doesn't make any sense. I tried different plug positions on my UPS... and when I plugged back into it, the LEDs lit up, but went right back out, again.

I went to my Win7 computer and started hunting for information to help me troubleshoot this thing. I became a little discouraged and started shopping for new PSUs... and even got into motherboards, thinking of upgrading the Core2Duo/Abit AB9 Pro setup to something more up to date.

Suddenly, while operating the Win7 machine near midnight last night, the LEDs all lit up on the problem child and I was able to start it, again. The black boot screen mentioned checksum errors, and I proceeded to the BIOS to set my defaults, since I had cleared the CMOS, earlier.

It's been doing fine, since then... so I am not sure what my next move, if any, should be. I have been threatening to reload XP, but that may not help the problem, and even though it would probably make things go smoother, I am not crazy about the prospect, but a clean system is attractive, aside from the sudden power down problem. But my question leans more towards the problem that shut the power down, and anyone who might have had this happen, before... and fixed it.

I'm dealing with an Enermax Liberty ELT500 PSU, the board and processor mentioned above, three gigs of RAM... a WD Black 250 gig boot drive and two WD Black 750 storage drives. CPU temps usually run in the low to high thirties, depending on how warm the room is... lately, that room has been hanging in the high seventies to low eighties... but I hope that's about to change for this year. Oh yes, and no warnings about low battery on the UPS.
Thanks

 

That check is good... I'm way over what I need, in overall wattage. The computer has been working like a charm since midnight, and I'm backing up files from the boot drive like crazy, all day today.

Since I don't have a problem with it, right now, I guess I'll have to wait until it messes up again... I just hoped that someone might have had this problem before and could suggest something that worked for them, so I can be ready the next time it messes up on me... or possibly prevent a subsequent episode.

I'll leave my question to run for a while, to see if we can resolve this thing... or have it drop out again, and maybe go unresolved.
Thanks

 

If there is a problem with Windows, the system restarts, from my experience, it does not shut down.

A shutdown would point to a hardware problem, although if hardware drivers are not "good ", the hardware can overheat and could cause a shutdown.

Is the battery in the UPS good? Have you tried bypassing it?

Is the inside of the case free of dust, particularly in the fins of the heatsink on the CPU? (Don't take the heatsink off the CPU, just loosen the dust with a straightened paperclip and blow it out.) Are the air intake vents clear of dust?

Checksum relates to the CPU, but you should just need to enter the BIOS and then just Save and Exit.

Matt

 

Ummm, not exactly. The checksum error indicates the hardware information saved in CMOS is different from the hardware seen during the boot. So it could mean the RAM changed, the drives changed, or any change occurred since the last CMOS save - or it could mean the CMOS information itself changed. This will happen every time you boot until you boot into the BIOS Setup menu, and Save and Exit. This assumes the battery is good. If the battery is bad, the CMOS setting will not be saved, or stay saved and the CMOS resets back to defaults, which of course, will not match the checksum the system finds next time it boots.

As for UPS, which I think all computers should be on, they have one major drawback. The batteries need to be replaced, typically every 3 years. The surefire way to test the UPS batteries is to pull the plug from the wall, simulating a power outage and see if your system stays up. Of course, if they are bad, your system will crash and you risk corrupting your drive. So I keep two 150 watt light bulbs handy that I use for battery testing.

If the ambient (room) temperature is high, that sure could be the problem, and you should be monitoring your temps. If your CPU temps are over 60°C, that could be your problem. There may be a setting in BIOS to shut down when the CPU temp reaches a set threshold, often 65°C. Don't change the threshold! Fix your cooling. Is the case interior clean of heat trapping dust? If not temps, then I agree, this sounds like power to me - at least I would want to start looking there first. You can look in the BIOS or use a monitoring program, but they are only as good as the sensor. Here's my canned text on testing PSUs.

To properly and conclusively test a power supply unit (PSU), it must be tested under various realistic "loads" then analyzed for excessive ripple and other anomalies. This is done by a qualified technician using an oscilloscope or power analyzer - sophisticated (and expensive) electronic test equipment requiring special training to operate, and a basic knowledge of electronics theory to understand the results. Therefore, conclusively testing a power supply is done in properly equipped electronic repair facilities.

Fortunately, there are other options that are almost as good. I keep a FrozenCPU Ultimate PSU Tester in my tool bag when I am "in the field" and don't have a good spare power supply to swap in. While not a certain test, they are better than nothing. The advantage of this model is that it has an LCD readout of the voltage. With an actual voltage readout, you have a better chance of detecting a "failing" PSU, or one barely within specified ATX Form Factor Standard tolerances. Lesser models use LEDs to indicate the voltage is just within some "range ". These are less informative, considerably cheaper, but still useful for detecting PSUs that have already "failed ". Newegg has several testers to choose from. All these testers contain a "dummy load" to fool the PSU into thinking it is connected to a motherboard, and therefore allows the PSU to power on, if able, without being attached to a motherboard - great for testing fans, but again, it is not a true load or suitable for conclusive testing.

Swapping in a known good supply is a tried and trued method of troubleshooting, used for years even by pros. If you have access to a suitably sized, spare power supply, carefully remove the suspect supply and replace it with a known good one and see if the problem goes away.

I do not recommend using a multimeter to test power supplies. To do it properly, that is, under a realistic load, the voltages on all the pins must be measured while the PSU is attached to the motherboard and the computer powered on. This requires poking (with some considerable force) two hard and sharp, highly conductive meter probes into the main power connector, deep in the heart of the computer. One tiny slip can destroy the motherboard, and everything plugged into it. It is not worth the risk considering most multimeters, like plug-in testers, do not measure, or reveal any unwanted and potentially disruptive AC components to the DC voltages.

Note the required voltage tolerance ranges:

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And remember, anything that plugs into the wall can kill. Do not open the power supply's case unless you are a qualified electronics technician. There are NO user serviceable parts inside a power supply.
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That is always a last ditch effort, for when everything else has been tried. There are too many downsides to reloading. For one, you end up months, or even years behind in security updates. You may be one or two service packs and driver updates behind. You also don't learn what caused the problem, or how to prevent recurrence. And besides, this is a hardware issue.

 

Wow, this is helpful... I have already ordered a PSU tester, prior to seeing this... should be here soon. But that's for when this thing stops again, I would think. It seems to be working like a champ... again. I could do some video work to see, but so far it's doing everything pretty well. Overall, this machine doesn't have a lot of problems, but it does kick out a glitch every now and then.

I happened to think about the history of this machine, and I have had similar shut downs, but it never failed to boot afterward, like this time. If I didn't have the cover off the side, I would have never known the LEDs went out... usually, I just turn it back on again, and all is well. Since it's a 24/7 machine, most of the time I never know exactly how it went down... only that it had either rebooted, or it was off and needed to be booted.

Temps are good. I keep an Abit uGuru bug running so I can monitor, and it is now reading 35 C. I recently swapped out the cases... from a Coolermaster Centurion T05 (tight) to a Coolermaster CM 690 II Basic (easy breather). I also added a 140 mm fan on top and improved the average idle temps during a good day, down about two degrees. Highest working temps during video work has been 43 C.

On a particularly hot day... over 100 outside, the CPU idle temps will rise to about 38... occasionally 39, but that's it. Temps on all my machines tend to be good... I never use stock coolers... picking the highest rated for cooling performance, while keeping an eye on pricing.

Dust is not a problem, now... the swap over to the new case took care of all of that... I cleared everything out and made it look like new. Had this happened before I let the last build go to my step-daughter, I could have swapped the PSU... they're very close... but I didn't have that luxury. Only one I have on hand is an old Gateway (Newton Power) 200 watter. It was also suspected of failure many years ago, in computer time.

I guess it's a wait and see situation, while it's still working. I'll check in when the PSU tester arrives, but if it's like my health problems, everything will check out fine. I may even pick up another PSU, just to have it on hand... and to give myself the beginning of my next build.
Thanks again

 

That depends on the tester. If it has an actual read out, you will be able to see (1) if the output is stable and (2) how far out of tolerance the voltage is. If it just uses LEDs, you don't really get a good idea of what is happening.

 

The one I picked was the Antec with an LCD screen. It may have some LEDs, but the description sounded pretty good. I figured a reputable PSU company would probably offer a decent piece of PSU test equipment. I'm such a frequent customer at Newegg, I was a little disappointed that they didn't have the Antec in their inventory. At least it shouldn't take very long to get to me... the vendor is just two states away in Georgia... hope the shipping warehouse is as well.

 

Update

Looks like I'll get the chance to check the new PSU tester... the old girl dropped again, while burning some data CD copies. Hasn't come back, yet... but I have another PSU on the way, right behind the tester. That worries me, now... the wife has the same Enermax PSU on her machine.
Onward and upward...