# Power supply, MB, or CPU failure, how do i determine which?



## 00trav (Sep 6, 2007)

Hi everyone,

First off thanks for any help in advance. I worked in tech support for 3 years and this problem is somewhat baffling to me. unfortunately, I don't have all the replacement parts I was used to working with or the test systems. So I am trying to figure out what is failing before taking 3 trips to the store buying and testing different parts.

so what happened...

First moved to new apartment, never had problems before that. within 10 minutes of turning computer (desktop), i was standing on the other side of the room, and system just turned off (didn't crash, just zap, no power). I didn't think anything at the time since i was still moving and messing with light switches and thought i randomly hit a cord or something.

a couple days later, after i had been using the computer for a while, games and all, one day i turn it one and it barely gets to the desktop and zap it turns off. First i think crash so i hit the power button to turn it on and nothing, no flicker no nothing. so i think power supply burnt up or MB fried. I curse in my head and go eat dinner. I come back after dinner and press the button for the heck of it and what do you know it works. worked all night, played games, cranked up the GPU. nothing no problems. i shut it down, check all the wiring in the back, everything looks solid. the entire 3 day weekend, worked great, lots of gaming.

This morning, turn it on to do some work, barely boots to desktop and zap, off again. press power button, no luck. By now i figure something is going on. I unplug and plug in, powers on for split second, then nothing, no lights on MB or anything.

Correct me if I am wrong, but i have pretty much ruled out hard drives, the Video card (one since its new, and two it isn't displaying GPU problems). 

I don't think its an overheating problem since I used it for long periods with no problem, its only on the initial startup that it powers off.

So i am down to whether its my Motherboard or Power Supply, or possibly my CPU. I have an Enermax 530 watt powersupply designed for SLI (which i am not currently using). I have a K8N Neo4/SLI mother board and an AMD 3500+ processor.

The part I find weird is that the power supplies that i have seen fail before, totally fail (once they go out they do not go back on). Also, i have checked the MB and haven't found any physical signs of it blowing (although i know that it doesn't mean its not bad). and also i figured that if its the MB or CPU i would get some beeps and powers till to the MB and fans.

Any thoughts

Travis


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## telegramsam (Jul 7, 2006)

Start with this:
http://forums.techguy.org/hardware/580000-troubleshooting-guide-problem-builds.html

Do the out "won't post" part.

It could be any of the things you listed, but it could be part of the motherboard grounding, a loose wire--like the power or reset button, or a loose heat sink causing overheating, even bad RAM...just to name a few things.
That process will help you scratch some of the easy stuff off the list before you go buy any replacement parts.


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## Ziggy1 (Jun 18, 2002)

I would say it sounds like the CPU, and it will be the easiest to check. And you should stop using your computer until you check or replace it, if it shorts out it can fry your board.

Did you also test your electrical outlets to ensure is is properly wired (grounded- hot/neutral), you can get a tester that just plugs into the socket for about $10....I always do that when I move.


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## 00trav (Sep 6, 2007)

first off, thanks for the quick replies. 
second i am more confused then ever. I stripped everything out of it. left only cpu MB and RAM. then took RAM out. 
at first everything was looking like it was the RAM, kept failing, untill i removed one DIMM and then everything good, then did a Memtest, one bad sector found, so i was thinking, okay its the ram, BUT it was running good, never zapped out. then i left for the night and returned later, turned it on and zap power out. so then i removed the RAM, same thing, brief flash and zap. i am completely confused.
its not an over heat thing because i had it on for over an hour doing tests last night and it didn't get that hot.
i also figured if the processor was bad the MB would beep or show other signs
I am completely confused, i don't understand why the problem is so intermittent. i feel like a faulty CPU or MB or PSU would constantly be bad.

as far as power to my apartment; i thought that was the problem at first but I bought a new surge protector, everything is grounded, voltaged according to the MB bios seems to be consistent. I think i am going to buy a volt regulator today and test to see if thats the problem but i am starting to think its something more.


any ideas of where i should start swapping components????


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## telegramsam (Jul 7, 2006)

So you removed EVERYTHING from the case, and hooked up ONLY the board, CPU+fan, video card, one stick of RAM, keyboard and mouse? I do mean everything, OUTSIDE of the case, no drives or anything else connected...

What did you get for a display when you run this test? Are you able to access the BIOS?
If you have the out of case build setup done correctly, you should be able to get a display and access the BIOS.


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## 00trav (Sep 6, 2007)

no, i didn't take it out of the case, i guess that will be my next step. but i don't think its the case. This is not a new system i just built, this is a system that i have had for almost two years, running smoothing. the only thing i replaced was the video card and that was 4 months ago, everything has been running fine up untill this issue happened.

as far as display.... works fine, when i am able to power up, i can get to the bios, i am able to view the temp of my cpu and mb and view the voltage. i was able to use an ubuntu cd to do a mem test, but... the second and third time i tried it zapped out.

the weird part is that once it zaps off, i have to unplug and plug it back in again in order for it to work. if i don't the power switch is dead.

I have unplugged everything else, all hard drives and other drives, i even unplugged the additional power to the video card. also, i tried removing the ram after the last time it zapped out and still couldn't get power after the ram was removed.

I am still baffled. do you think its really necessary to take the board out of the case?


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## Ziggy1 (Jun 18, 2002)

I just realized I made a Typo, I meant PSU not CPU, but maybe you figured that is what I meant.

I was looking on the Enermax site and saw this issue that sounded similar to yours, now obviously you have all the components installed and it was working, but the indication that the PSU checks the min load could mean that that function is malfunctioning? it could just be that at some point the "load" is dropping to the point to where the PSU shuts down.

* is there a way to log this?

http://www.enermax.com/english/service_faq.asp#faq1

(Text from link)....

_A1: Except for the maximum output limitation, there is also the minimum load requirement of the PSU. (The minimum load requirement of the ATX12V form factor is about 15W.) If system loading fail to meet PSU specified DC minimum load requirement, the PSU might not be able to maintain the DC voltage output stability. In this situation, the PSU will stop working in prevent system damage.

Also

Now it has been confirmed that discontinued EPS12V EG851/651AX-VH (W) FM power supply might not be compatible with new Intel Core 2 Duo or AMD AM2 energy saving design CPU PC system. 
This power supply series is designed base on 2003 SSI EPS12V power supply design guide for server/workstation application, which allows +12V1 and V2's minimum load requirement up to 36W. However, nowadays PC system's new energy saving CPU could consume less than 15W power in boot up sequence or in system idle mode. As the result, this will not meet this power supply's minimum load requirement and will turn off the system for protection.
From 2006, ENERMAX power supply series has modified the specification to meet new PC system eco design and would not have this compatible issue.

This occurs more with the dual core processors with energy saving design introduced after Q3 2006. Due to the very light CPU +12V power draw at boot-up stage, it fails to meet the +12V minimum output loading condition of the PSU, therefore, the PSU will turn off automatically for protection. Once you add a HDD or ODD, this will meet the PSU minimum load requirement, and everything will work fine._


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## telegramsam (Jul 7, 2006)

Leave the video card power plugged in. Make sure the 4-pin CPU power harness is connected too.

You do the out of case build because of grounding issues or loose wires. It can happen, and the idea is remove anything that might be causing a problem and get to the core components. Removing it from the case is critical to the process.


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## 00trav (Sep 6, 2007)

just wanted to give you guys a thanks,

I figured out the problem, 
i believe the transistors or the capacitors in the power supply were going out, which caused the interment nature of the problem. 

i put a new power supply in and it works like a charm, I guess i am just lucky it didn't take my whole board and CPU with it. I am trying to get in touch with enermax so i can get a new PSU, but they don't answer their phones and don't return phone calls, which makes me very unhappy. Needless to say i am sticking with antec from now on

thanks again all


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## Kristjanna (Oct 24, 2007)

I had a similar problem. However the computer would only restart/reboot while doing a AVG scan or an ad-aware scan. Sometimes however AVG would do a scan, the crazy thing was it would change the amount of objects it scanned. i.e: 400 objects scanned, when really there is over 70000, it changed each time. I assumed virus/spyware, so format reinstall XP. still happening. Tested Ram..a.o.k. problem still there. Everything was fine with drivers, racked my brain, swapped everything in the case, power supply was good, hardrive got new....
After everything, it ended up being the processer. Replaced that with a new one (had same one in a different system) and it works just fine... 

Just thought I would pass that on, since once in awhile you do get a problem that almost never happens.

~Kristjanna


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## MichaelDee (Oct 15, 2007)

I had a similar problem, my pc would maybe run for 2 minutes or a day without shutting off (like a power failure in the house). I'm lucky enough to have extra psu's, so I changed the psu, and my pc ran fine for several days without restarting or shutting off. I switched back to the old psu (it was only about a month old) and it starterd shutting off again intermittently. A psu tester wouldn't detect it, but intermittent problems are sometimes hard to diagnose, and usually wont occur when you want them to, lol.

http://www.tigerdirect.ca/applications/SearchTools/item-details.asp?EdpNo=1647108&CatId=1107


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