My computer keeps shutting off

May 9, 2009 at 09:05:54
Specs: WIN XP Pro/SP2, AMD Athlon64 3200+
Hi Everybody,

I have a custom built computer that has has been giving me problems lately. A summary of my system:

A8N-SLI Motherboard
AMD Athlon 64 3200+ CPU
NVIDIA GeForce 6500 Video Adapter
Maxtor 160GB SATA Hard Drive
Western Digital 320GB SATA Hard Drive
IDE DVD Lightscribe
550W Dual Fan Switching Power Supply
Windows XP Pro/SP2

What my problem is, is that the computer keeps turning off unexpectedly. When it does, it will try to reboot but when it does it won't find any hard drives. I know this because none show up in the BIOS although my DVD drive does, and it is and IDE device. A message will come up saying: DISK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS ENTER. Well I know there's nothing wrong with my Operating System, it just can't find the hard drive. It has been doing this for a few days all of a sudden. I have several times turned the power switch off of the PS and held in the power button to dissipate any power on the board and then restarted the computer and this has worked many times, so I know everything is still there.

Then the BIOS will detect the hard drives. After that it will boot up and be ok for a while until it does the same thing over again. This morning, sometime through the night, it happened again. This time I had to change around some power connectors and finally got it up again and it's working fine for the moment.

This is a new power supply so I'm trying to rule that out, but it just seems that it is not getting power to my hard drives even though I know it is cause the system is up and running fine when it is.

The hard drives would probably not show up in the BIOS if either they were not receiving power, or data I think, but the only common connection that was linked to both of my hard drives was the power cable that I was using to connect both of them together.

I've checked the event log and although there are some errors and warnings, it doesn't correspond with the time the computer went down. It shows it's ok at 2:30AM then nothing till 10:22AM, when I got it back up again.

When my computer is up and running it works great, but then there's that time when it seems to lose power, so how can that be? If there was no power coming through my connections it would never start . I'm just so frustrated and confused.

I had thought about the CMOS battery being bad or dead but after the computer is up, shouldn't it be ok? I hope someone knows or has some good idea what the heck is going on with my computer. HELP!!!!!!!!!!!


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May 9, 2009 at 09:53:16
Random shutdowns/restarts can be caused by several things...overheating CPU, failing power supply, bad RAM, driver conflict, infection, etc.

The 1st thing you need to do (if you haven't already) is disable the auto-restart option...that way a blue screen error message will be displayed which *should* help you to identify the problem.

Other than that, this PSU description is very suspicious: "550W Dual Fan Switching Power Supply". How about a brand name & the amperage ratings on the +3.3v, +5v & +12v rails? The +12v rail is the most important. If your PSU has multiple +12v rails, each should be 18A. If it has a single +12v rail, it should be at least 30A. The +5v rail should be between 20-30A. If it's say, 50A, it means the manufacturer deliberately "hid" power on the +5v rail to falsely inflate the PSU overall wattage rating. An extra 20A on the +5v will increase the rating by 100W but it will never be needed or accessible. Also, a decent quality 550W unit costs $50 or more...if you paid significantly less or the PSU came preinstalled in the case, you can be fairly sure it's a low quality generic unit.

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May 9, 2009 at 11:42:25
Hey jam,

Thanks for the reply, the power supply I have is one I purchased locally from Premier Computer Services. I hadn't heard of the brand but I needed one. This is it:

But I have to suspect my power connections because I have it connected to a molex connection at a different location on the wires and it has been up now for several hours. It also has SATA power but I was having the same trouble with that. So anyway, I still don't really know what to do. If it is the power supply, I don't know how I could prove it, besides I don't think they'd take it back. So thank you and any other comments or suggestions are welcome.


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May 9, 2009 at 18:17:28
What I can't understand is when it shuts down, it always cannot find the hard drives. They do not show up in the BIOS but my DVD drive is always there. If it was a power issue then why does the DVD always show? I am wondering if it could be my motherboard? There is about a month left on it's warranty.

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Related Solutions

May 11, 2009 at 09:43:19
Its sata/ide problem! update your bios to the latest drivers (IF u know how to do it - if u dont know dont try it) check the bios for sata cotroller to be set as IDE! and then change ur thermal paste on the cpu

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May 15, 2009 at 13:50:06
Take out your CPU and apply some thermal gel to it

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