Computer Help

[George Bokros]

Our desktop system will not turn on. Press the power button and nothing. It shut down last night when we had a power interruption. I did have trouble getting it to tur on Monday when I shut it down so I could shut the power off to install a ceiling fan. I probhad the power supply checked and it tested good. I ran a continuity test on the switch and it passed. I have the hard drive now mounted in an external cabinet so we can access our data.

This is a 10 yr old machine running XP and is the one the wife uses and also the place we keep all our data files and backs up to Norton on line automatically.

I am puzzled what could the the issue. I see not evidence of any kind on the mother board. Like I said it is a 10 yrs old Dell with a quad core processor.

Any ideas of what to check? I really would like to avoid the $550 for a new desktop computer.

[Jerome Stanek]

If you can't get it to boot up you may want to look at Microcenter in Mayfield for a refurbished one they have some good deals. I bought 9 different computers there and have had real good luck with them. You can look up what they have online and reserve it and pick it up in without standing in line

[Larry Frank]

Check easy things first....surge protector, circuit breaker,GFCI

The computer should at least try to boot with t h e BIOS. If it is not doing that check the power supply.

If the computer is starting to do the BIOS and not booting then sounds like hard drive.

Good for you that you have a back up....most people do not do that.

[George Bokros]

Check easy things first....surge protector, circuit breaker,GFCI

The computer should at least try to boot with t h e BIOS. If it is not doing that check the power supply.

If the computer is starting to do the BIOS and not booting then sounds like hard drive.

Good for you that you have a back up....most people do not do that.

Definitely not the surge protector, won't boot an another outlet without the surge protector.

Does not boot the bios, the fan on the power supply does not even start nor does the case fan or the fan on the CPU.

Power supply has been tested and checked out as good.

Hard drive is in an outside cabinet and I am able to access from my other computer.

[Chris Parks]

Faulty power cord?

[John Coloccia]

If the power supply fan doesn't turn, what makes you think the power supply is good? Anyhow, have you tried unplugging it for a few minutes and plugging it back in? Some protection component may have tripped and needs to cool back down. That switch on the front is not a hard power switch. There's probably a real power switch on the power supply itself. It sounds to me like the PS is just unhappy. Computers are actually pretty robust. It's usually the power supply that's dead in cases like this, and hopefully whatever is unhappy will just reset when you've powered it off for a while.

[George Bokros]

I took the power supply to a computer service tech and he tested it. It has been off for several hours.

[Gerry Grzadzinski]

I agree with John. I'd try a new power supply first. If that's not it, then it's probably a dead motherboard.

[Larry Frank]

Check connectors between power supply and motherboard.

It seems like you have checked everything logically.

[Lee Schierer]

Sometimes the little lever that touches the microswitch that turns it on can fail. Open the computer case and press the mircoswitch by hand.

[Phillip Gregory]

If somebody tested your power supply unit (PSU) and it tested OK, then there are only a few remaining things that can go wrong that would cause absolutely nothing to happen when you press the power switch. The power supply's signal to turn on and provide any power to the computer is by the POWER_ON pin in the motherboard power connector (the one with the green wire) being pulled to ground by the motherboard. The motherboard's sign to do so is by the case power switch temporarily completing a circuit.

1. Your case power switch's connector leads have become loose from the header on the motherboard, therefore the switch does nothing.
2. Your motherboard is defective as it is not recognizing the case power switch being pushed and therefore is not pulling the POWER_ON pin to ground to turn the PSU on.

I'd check the case switch leads to see if they are loose, otherwise your motherboard is toast. You mentioned it is a 10 year old Windows XP system so I am strongly suspecting it is the motherboard. Motherboards 10 years ago had the bad combination of often subpar electrolytic capacitors plus some very hot-running processors such as the Intel Pentium 4. I have a grand total of one system from the early and mid-2000s still running and it uses an unusual very low-power blade server motherboard, so it's not hot and it is a very high quality piece of equipment (motherboard alone cost about $400 when it was new.) ALL of the others had their motherboards die on them.

[John Coloccia]

You think he's a victim of the capacitor plague, Phillip? A glance at the motherboard caps should diagnose that. See any cylindrical looking things that look puffy with goo running out of them?

[Phillip Gregory]

That sounds pretty probable given the age of his gear. A lot of P4, K7 Athlon, and DDR Athlon 64 boards died of the capacitor plague after about 3-5 years of pretty routine use and lasted a few more years if they were only used occasionally. One place I used to work replaced all of its computers on a 3-4 year cycle but stopped when they realized that the Pentium Ds their vendor was selling then really had no advantages over the giant crop of 2.4 Northwood P4s running Windows XP and Office 2003 they already had. So they sat out a complete upgrade cycle, which hilariously enough left a modest number of "tag-along" out-of-upgrade-cycle PIII 866s running XP still kicking along in the later 2000s. The PIIIs simply became too slow to do any work but didn't die. The Northwood P4s however started to die pretty regularly after about 5 years and there were a lot of various late Pentium Ds and a smattering of early Core 2 machines gotten as one-off replacements until they decided to get back up on their upgrade cycle rather than be stuck with a mess of dissimilar machines. My next employer ran post-bad-caps HP Socket AM2 machines from when they bought them in 2006 until just before I left in 2014. They upgraded only because the now-outsourced IT department said they absolutely HAD to upgrade from Windows XP due to lack of MS support, and HP didn't want to provide Windows 7 drivers for those old AM2 machines. Very few of those machines had any trouble besides the usual dead HDDs and PSUs.

That pretty well mirrors my experiences with things at home too. Old stuff lasted forever unless a PSU blew and killed it. Every P4, K7 Athlon, and DDR Athlon 64 board died within 5 years. Most had visibly bad capacitors. Anything newer is still running, and some certainly run hotter and use a bunch more power than a typical Pentium 4 desktop.

[Chuck Wintle]

Our desktop system will not turn on. Press the power button and nothing. It shut down last night when we had a power interruption. I did have trouble getting it to tur on Monday when I shut it down so I could shut the power off to install a ceiling fan. I probhad the power supply checked and it tested good. I ran a continuity test on the switch and it passed. I have the hard drive now mounted in an external cabinet so we can access our data.

This is a 10 yr old machine running XP and is the one the wife uses and also the place we keep all our data files and backs up to Norton on line automatically.

I am puzzled what could the the issue. I see not evidence of any kind on the mother board. Like I said it is a 10 yrs old Dell with a quad core processor.

Any ideas of what to check? I really would like to avoid the $550 for a new desktop computer.
If the PSU tested good then probably the MB or CPU has died and needs changing. Interestingly my old computer bit the dust last week and the MB and cpu have failed. See if you can swap in a new MB and CPU. How did they test the PSU?

[George Bokros]

If the PSU tested good then probably the MB or CPU has died and needs changing. Interestingly my old computer bit the dust last week and the MB and cpu have failed. See if you can swap in a new MB and CPU. How did they test the PSU?

Don't know how they tested the power supply,they took it in the back room to test it. I am sure if it was tested properly it tested good because they had the perfect opportunity to sell me a used power supply,

[Wes Thom]

Don't know how they tested the power supply,they took it in the back room to test it.
A perfect example of why recommendations must be preceded by first learning how it works. And why changing things before identifying a problem can even exponentially complicate matters.

PSU only powers on when ordered by a power controller. That controller has many inputs to decide when to power on or off. CPU is not even permitted to execute until the controller permits it. Front panel (intermittent) switch is only another controller input.

Your PSU will not power on if a controller does not order it. PSU is only one of many components in a power system. To obtain useful replies requires a meter, some requested instructions, and minutes of labor. Resulting numbers from six wires will clearly exonerate or accuse an appropriate suspect. Then a defective part and only the defect part is replaced.

Two options. Keep replacing good parts until something works. Shotgunning is often recommended when basic functions (ie power controller) is unknown. Or better techs disconnect nothing, use a meter, and identify a defect in a minute. Those are your two choices.

Of course, some will overlook the obvious. Connect an incandescent lamp to that wall receptacle. If it illuminates, then connect the computer directly to that same receptacle. This (sometimes overlooked) fault is eliminated that quickly.

[Phillip Gregory]

A perfect example of why recommendations must be preceded by first learning how it works. And why changing things before identifying a problem can even exponentially complicate matters.

PSU only powers on when ordered by a power controller. That controller has many inputs to decide when to power on or off. CPU is not even permitted to execute until the controller permits it. Front panel (intermittent) switch is only another controller input.

There are three ways to test a PSU.

1. Plug the PSU into a known good motherboard and hit the case power switch. If the known good motherboard boots, and yours does not, the PSU is fine.
2. Short the POWER_ON pin to any ground pin and then measure to see if you get anything remotely resembling +12V, +5V, and +3.3V at the appropriate pins. This will say if the PSU is not totally fried, but you can get wild swings in voltage that will not allow you to boot a motherboard once you put any load on the PSU if you have a faulty PSU. This is really an extremely quick and dirty "should I even bother to plug it into the test motherboard?" kind of test.
3. Connect the PSU to a specialized PSU load tester and load it up while watching voltages. If everything is within spec at full load, the PSU is absolutely good. This is very rarely done as these units are expensive.

I'd just about guarantee that they did 1) and plugged it into a known-good motherboard, which booted properly.

The power supply has only one way to know that it should turn on. The POWER_ON pin gets connected to ground, causing a voltage change in the POWER_ON pin that turns the PSU on (see #2 above.)


Your PSU will not power on if a controller does not order it. PSU is only one of many components in a power system. To obtain useful replies requires a meter, some requested instructions, and minutes of labor. Resulting numbers from six wires will clearly exonerate or accuse an appropriate suspect. Then a defective part and only the defect part is replaced.

This sounds like the quick and dirty test in #2 above, and unless you have a load connected you can't really trust if your voltages are in fact good. About the only way the "short POWER_ON to ground" test is useful is if you get nothing or if the voltages are way off, like +10.5V on the +12V rail for example.

[George Bokros]

Thanks for all the input. Problem solved--- new computer purchased. Now the ugh of setting up it up on the network, loading software continues. So far so good. The old computer was 10 yrs old so putting money into it was not something I felt I should do.