My PC won't stay on!! Power supply failure? 1

[johndog]

Hi,
I'm not sure if my PC is having problems with the motherboard or with the power supply. I'm running a 2.5ghz P4, 40gb HD, 256MB DDR, on a Gigabyte motherboard. The motherboard has a daugtherboard on it that is supposed to support the power distribution from the power supply. A while back, my computer would mysteriously shutdown on its own. Now when I try to turn it on, the fans spin for about 1 second and then the PC is dead. After pressing the power switch several more times, nothing happens. If I wait a few minutes and/or unplug the powercord, the PC will do the same thing, run the fans again as if it is booting up but only for 1 second.

My concern is that the motherboard is having problems, but I'm not sure how to find out. I tested my powersupply on another PC and it booted up just fine, so I think the powersupply is ok, but I'm also not sure if it just won't work with my P4. Any troubleshooting help is greatly appreciated.

 

[jurgen36]

Power supply: I am very sure, had the same problems with about 30 machines. Comes on for a few seconds and nothing happens. Need at least a 400 watt supply. Regards

Jurgen

 

[johndog]

I have been using a 350 watt powersupply on this PC for about a year now. Since the powersupply has had no previous problems and booted my other PC (an AMD 800 on Abit MB), I have reason to believe that the powersupply is ok. Could part of the motherboard be bad (Gigabyte P4 Titan SINXP1394)? How can I be sure if it is the CPU? Thanks again.

 

[paparazi]

johndog
Not meaning to be critical but you arn't taking any notice of experienced advice but falling into the trap of assumption.
An AMD 800 setup is probably drawing 70% of the power when compared to the P4, that's probably why the PSU appears to be running fine.
My only suggestion is to pull off everthing but the bare minimum to see if less load will allow the system to boot.
Unfortunately at this level everything is a calculated guess, the only real way of knowing is to swop out. Now I know that is a problem but unfortunately that's what it often comes down to.
Is this a 533fsb CPU? think that board only goes upto 533?
Martin


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[amandawhite]

power supply cheaper to replace than cpu, id start there, process of elimination.

 

[Grenage]

I too would suspect the Power Supply as the most likely culprit.

 

[BadBigBen]

It could also very well be that the HS Fan is clogged with DUST and such, or the plug is loose, or the FAN isn't mounted correctly on the CPU? As P4's aren't prone to 'Death to HEAT' (integrated logic that turns off the PC before it gets to that point)... I would start with resetting the CMOS first (could well be bad settings)... then go with what the others suggested, switch out the PSU with a GOOD 400 watt PSU and keep the old one as a spare for lesser PC's... make sure that all cards (PCI and RAM Modules) are seated correctly... make sure that all cable connections are properly and tightly installed... clean out DUST (if present)...

Ben


If it works don't fix it! If it doesn't use a sledgehammer...

 

[jurgen36]

That are exactly the same bords we were using. FSB only 533 Mhz, extra supply bord for the CPU etc. Well with us it was the supply. Worked ok in other machines but not with P4 CPU's.
Good luck.

Jurgen

 

[johndog]

I appreciate everyone's help. BTW, I'm pretty good with computers, I've built probably over 30 custom machines and I service them all of the time. In fact, my job is to do so. This is just a problem I want to be certain of before I go an spend a bunch of money.
The main reason for my concern is that I've been running this powersupply for almost a year without any issues. So if it was in fact the powersupply going bad, why would it still work with my AMD processor? I understand that the P4 would use more power, but is has been fine for a long time which gives me reason to believe either the CPU or motherboard has gone bad. Thanks again for all of your help.

 

[danomac]

350w isn't really enough for a power supply. Also, noname brands of power supply units would not be able to even produce 350w reliably. It's all about wear and tear on the PSU itself. If you are constantly drawing at the PSU's limit it will wear faster. Batteries also can show this type of wear - just because a 12 volt battery shows 12 volts with a meter does not mean there is usable current there to back it up. For example, if you take batteries from an external flash from a camera that won't operate the flash anymore, and you put them in a remote control for a TV, it can still work. Why? The remote doesn't take as much power to operate as the flash. Same with your P4 and AMD.

 

[hthb]

Isn't the computer supposed make some special combination of beeps if the CPU is fried?
Otherwise, if you have made any upgrades to your computer the new component may been consuming excessive amounts of power (for instance, graphics card).

There is also the possibility that the motherboard or some other component is touching the case. Then the mobo is grounded and no power goes through. I once had that problem, took me 6 months to realize what the problem was, after taking a course in Electrical Engineering which required you to build your own power supply.

Hope you fix it, good luck!

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[johndog]

Part of the problem is that the computer does not stay on long enough for me to tell whether or not the motherboard or CPU is bad. It turns off way before any warning beeps would sound. I think it is a good suggestion to check and see if the motherboard is touching the case. I highly doubt that it is, since I haven't moved the computer around much but it is worth a shot. Thanks for all of you help. BTW, how long was your computer on before you figured out that the MB was shortcircuiting?

 

[johndog]

Good news folks! The computer that I'm typing this message on is the very computer that wasn't working! It was in fact the power supply. So what I did is swapped the powersupply out from my AMD and put it in my P4 and vice versa. Now both machines are working great! Thanks for all of your help!

 

[jurgen36]

There is a real danger using the old supply in another computer. There is obviously something wrong with the PSU. We had the case that the power supply had intermittend momentarely voltage drops. If at this time (most likely) the hard drives are writing, it will cause hard errors on the drives. We had this problem before. Everything worked ok but after a short time the HD packed up. Replaced the drives 3 times before I found out with a scope that the supply had very short voltage drops on the 5 and 12 volt lines. So be careful a supply can dammage your drives. Regards

Jurgen

 

[johndog]

Thanks for the tip Jurgen. I think what I'm going to do is buy a 400 watt PSU for my P4. I will then put the 350 PSU from my P4 back into my AMD. I definitely don't want my 80gb HD to die. Thanks again.