# Comps that don't turn on



## sasaki (Dec 12, 2006)

So far, I've witnessed three instances where a computer ceases to function for no apparent reason. The first was a Dell, the second and third were customs. Both the Dell and the first custom computers were my girlfriend's. The Dell stopped functioning, though the Power Supply was still functioning as it always had, it wasn't powering the motherboard. pressing the power button was like pressing the power button on an empty case. The Dell had been used for a year and a half. The same thing happened to the custom computer (IIRC: 939 4000+ Clawhammer, DFI Lanparty NF4 SLI-D, 2GB OCZ Gold, eVGA 7800GT, Seagate Baracuda 300GB, OCZ Powerstream 520W, Not OC'd) only it worked almost flawlessly for almost a year. Now, my friend's new computer did the same thing after 2 weeks (He has a very similar system to mine. IIRC: Gigabyte NF590-SLI S5, AM2 x2 5200+ Windsor, 2GB XMS2, XFX 8800GTX single, 4x Seagate 250GB, Silverstone Zeus 750W).

Now, both of them want me to fix the problem. My first guess is the power supply. I remember an older system I built that did the same thing, but it was as simple as replacing the Power Supply. I guess that means I've witnessed the same problem four times, not three.

Anyway, what do you folks think? Is it a dead power supply, or is there a lack of power in general? The Silverstone Zeus 750W may not be enough for the 8800GTX, even though it's SLI certified for a pair of them. If it's not, then I need to replace mine.


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## Xipoid (Dec 12, 2006)

That could be a few things

Does it not boot?
Do the fans spin?
Do any LEDs activate?
Does anything happen at all?


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## nrr (Dec 12, 2006)

One of the first things I'm going to suggest, if you do this sort of thing often, is to invest in a good power supply tester.  AT power supplies were really easy to test, but the newer ATX kit kind of likes to throw a fit sometimes, so a little bit of additional help is needed.  It's pretty much just a big resistor with a switch and the right connections to make the power supply power on without having to be hooked to a 20-pin (or 24-pin...) motherboard connector.

If you can, get one that'll let you test the -12V, +12V and 5V sources using a multimeter just so you can determine that they're within tolerance.  It's worth noting that having your 5V source even a hair off will most likely cause a lot of really, really important hardware not to function properly.

Now, as far as troubleshooting this goes, I'm going to ask the very same questions that Xipoid already has asked, so I'm not going to repeat them here.


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## CyberFoxx (Dec 12, 2006)

Well, if you can't afford a power supply tester, make sure ya get a good enough power supply to test with! My friends at the local computer shop use Grond, the ub3r PSU. I've actually seen this sucker bring "dead" motherboards back to life. Sadly, Grond is the only thing to actually make those "dead" boards work, normal PSUs just don't cut it. This is mostly because the motherboard is dead due to a short somewhere, and Grond just isn't all that gentle.

I myself have a el'cheapo 300-watt Acer PSU, with a dead fan, that I use for testing. Nowhere anything like Grond, but it works. And I've used it to kill many a board, on purpose that is. ^_^


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## sasaki (Dec 12, 2006)

Xipoid said:
			
		

> That could be a few things
> 
> Does it not boot?
> Do the fans spin?
> ...



No
No
Only the LED on the back of the PSU 
No

It might be worth noting that the LED on the PSU has 3 colors. Red, orange, and green. Because the manual and other online sources are vague as to what each color means, I only know that green means DC power is being supplied to the rails, and red means there isn't any power being supplied to the rails. I'm not sure what orange is, but while the system is off, the light is orange. When I turned on the power the light turned red.


Edit: My friend just told me that the light on the PSU used to turn green when he turned it on. it wasn't until recently (after it failed) that it turned red. Everything has cease functioning like an empty case.


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## sasaki (Dec 12, 2006)

Wiegraff said:
			
		

> Possible causes:
> 
> Totally fried/disconnected RAM
> fried processor
> ...



It's not the RAM because the system would attempt to post. Same goes for the videocard. It won't display but it will attempt to post. I know of that issue because I've dealt with it and had to RMA it.

I also helped my friend test the hardware before installing it in the case to make sure the RAM, Videocard, Processor, MoBo, and all four Ram slots are in working order. It would post and everything.

Also, I removed the power switch and used a small flathead to jump the power button connector. Same effect as the button.


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## CyberFoxx (Dec 12, 2006)

Wiegraff said:
			
		

> Totally fried/disconnected RAM



I honestly can't see RAM being a problem. Either a stick of RAM exists, or it doesn't, problems with the RAM wouldn't prevent a POST. And if there's no RAM detected, you get three long POST beeps. Motherboards only need three things to actually POST, power, the board itself, and a CPU. (Although, I did have a 486 that would POST without a CPU, you'd just get a "CPU Missing" screen from the BIOS.) And by POST'ng, I don't mean successfully and then loading the BIOS, I mean just doing the Power-On Self Tests in general.

On ATX boards, shorting the pins for the software power switch with a screwdriver is quite safe, just make sure it's the right ones! And most boards have the PC speaker built-in. So a good way to test a board, take everything off of it, just leave the CPU in, the PSU connected, the PC speaker if it needs an external one, and short the software power switch.

If nothing happens, it means one of these things:
You got the wrong pins. (Been there, done that. Stupid misprints in manuals...)
You forgot to plug the PSU into the wall. (Been there too...)
The PSU's plug isn't seated correctly into the motherboard.
The PSU is dead.
Maybe, just maybe, the BIOS might be fried.
Or just a plain outright hardware failure of the motherboard.

Now, about the BIOS maybe being fried. Most boards, 99% of them these days, do have a very, very basic backup ROM BIOS if the main firmware BIOS does get overwritten, or dies. Most of these will do one of two things, expect a floppy disk with a BIOS image on it, or expect a floppy with a BIOS image on it and beep like crazy.

What's nice these days is that some motherboards have a stand-by LED on them, makes diagnosing if the PSU is OK alot easier. Although it's powered by the +5v stand-by rail, it's still a decent indicator.

But yeah, just try with just the motherboard, CPU and PSU. That way you can keep out any "external" problems from HDs, Video Cards, RAM, etc. After you do that, start putting things back in piece by piece, starting with RAM.


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## sasaki (Dec 12, 2006)

This might be helpful to figuring out what happened.

My friend told me some more about what happened before it failed. He had turned it on and had it running idly while he was doing things around his room. He got back to his desk to do some paperwork, and the computer prompted him as if he connected his headset to the integrated audio port. It was plugged in for a few days. He just clicked "OK" and continued his paperwork. Then his monitor said no signal. The computer had turned off. He couldn't get it to turn back on after that.

This brings me to believe its either the motherboard or the PSU.


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## nrr (Dec 12, 2006)

sasaki said:
			
		

> This might be helpful to figuring out what happened.
> 
> My friend told me some more about what happened before it failed. He had turned it on and had it running idly while he was doing things around his room. He got back to his desk to do some paperwork, and the computer prompted him as if he connected his headset to the integrated audio port. It was plugged in for a few days. He just clicked "OK" and continued his paperwork. Then his monitor said no signal. The computer had turned off. He couldn't get it to turn back on after that.
> 
> This brings me to believe its either the motherboard or the PSU.


This sounds like a grounding/shorting issue to me, so I'd be more inclined to look at the PSU.  If you can, see if there're any overcurrent protectors on the PSU of any kind and see if they're tripped/blown/whatever.

If not, eh, it's time to do some circuit tracing or something. :wink:


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## sasaki (Dec 12, 2006)

nrr said:
			
		

> If not, eh, it's time to do some circuit tracing or something. :wink:



Or RMA it already. It's still under warranty. I don't see the reason to go through all that trouble if I can get it repaired/replaced. I'm going to have to RMA it if it's broken anyway.


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## nrr (Dec 12, 2006)

sasaki said:
			
		

> Or RMA it already. It's still under warranty. I don't see the reason to go through all that trouble if I can get it repaired/replaced. I'm going to have to RMA it if it's broken anyway.


Well, given that mentality, just RMA the whole kit.  RMA, RMA, RMA!

Get some sense and start doing just a little bit of digging to make sure you're not shipping back what isn't truly fouled up.  For all you know, a static ground short could have nailed some peripheral device that you're not even looking at.  This happens, and it's been known to cause machines not to power on.

Trace the circuit and see if you can find a problem before you instantly toss your hands up and yell, "RMA!"  You'll actually save a little bit of time in the long run too as opposed to being an excited Freakazoid about the whole mess.


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## sasaki (Dec 12, 2006)

nrr said:
			
		

> Get some sense and start doing just a little bit of digging to make sure you're not shipping back what isn't truly fouled up.  For all you know, a static ground short could have nailed some peripheral device that you're not even looking at.  This happens, and it's been known to cause machines not to power on.
> 
> Trace the circuit and see if you can find a problem before you instantly toss your hands up and yell, "RMA!"  You'll actually save a little bit of time in the long run too as opposed to being an excited Freakazoid about the whole mess.



If I had the equipment, sure. But I don't. It will cost me more time and money to do what you're suggesting.


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## kyubi_youma (Dec 15, 2006)

<_<>_> speaking of dead computers......my computer is a zombie. i accidentally zapped the mother board straight from the power supply.it wouldn't turn on........ then three days later it magically booted up (no new anything inside it in fact i just left it alone opened up and taken apart......) thus my computer=zombie  (some weird crap right there)


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## Kougar (Dec 17, 2006)

Any luck with them Sasaki?

Going back to the top, a Silverstone Zues is more than enough for a single 8800GTX card. I think I saw those draw less power than two x1900's in Crossfire. The status lights represent Orange = Standby Mode, Green = Normal Operation, and Red = Fault Condition.

Manually shorting the start pins was a good idea... usually when computers start to repeatedly go dead like this I'd start to question the power quality from the socket. Bad power will quickly shorten or even kill the best quality power supplies, so if neither uses a backUPS or something as a line conditioner then if it's the case it'll just happen again. If ya are still looking for things to try, removing all the RAM or the vid card might get you some error beeps from the system boards. Re-seating all of the power connections and various components, before stripping the machine down to the barebones is worth a shot.

I've not had much experience with PSU testers, but the $20 handheld ones aren't really worth it in my respectful opinion. I bought a cheaply priced, fairly heavy 400watt unit locally at a junk sale and it had tested clean across the board.. turned out to be so cheap because it blew after about 2 minutes in a bare P3 rig anyway. It even still turns on and runs briefly, and tests out okay. Was only a few bucks lost, but it quickly killed any faith I had in those "PSU testers"... to test a PSU you need to put a good load on it.


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