[paul_]

ok guys so in the last 2 weeks or so my computer has been shutting off randomly usually during the night when im asleep, in which case i just assumed my power supply was going. When I booted my computer up again it worked flawlessly so I didn’t think much of it.

today I came home from work to find my computer off, now I tried to boot it on and all the lights go on and all the fans start spinning, then 2 seconds later it shuts off now I figured this was just my over clocking or some settings in my bios so I went to restart my CMOS jumper and I put it on the clear position and I tried to turn on the computer and it turns on and all the fans and lights go on and stay on the only problem is nothing happens windows doesn’t load and I get no splash screen. So i put it back to default jumper setting and again it turns on for 2 seconds and turns off.

Anyone know what’s happing here

amd athlon 64 x2 3800+ at 2.4ghz
geforce 7800gt
250gig harddrivve w/ 16mb catche & 20gig hd 8mbs/catche
abit kn8 ultra mobo
dvd rom drive
cd rom drive
winxp sp2

Thanks in advance
-paul

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Hello,

This sounds like a PSU regulation problem. Either that or the motherboard. Take a close look at the capacitors on the motherboard to see if they are bulging. Any bulging caps are blown. If you can get your hands on a DMM, disconnect all power connections to the MB, hard drives, etc, then measure all the voltages at one of the power connectors. It's probably a 12v rail that's failing regulation. If it's bad, you'll see a very unstable voltage reading on the DMM. You can test the power supply by following the information on this Page. Please use caution while testing the PSU.

[makai]

Hello,

This sounds like a PSU regulation problem. Either that or the motherboard. Take a close look at the capacitors on the motherboard to see if they are bulging. Any bulging caps are blown. If you can get your hands on a DMM, disconnect all power connections to the MB, hard drives, etc, then measure all the voltages at one of the power connectors. It's probably a 12v rail that's failing regulation. If it's bad, you'll see a very unstable voltage reading on the DMM. You can test the power supply by following the information on this Page. Please use caution while testing the PSU.

[paul_]

ok i just looked at the mobo and graphcs and i dident see any capacitors that were buldged leaking or blown

now on the back of the pwoer supply theres a red switch that u can change the voltage or somthing. when i move the switch all the way over to the right so it shows 220 and i turn the computer on all ym fans will spin and all my drives and lights will turn on but i see no splash screen or anything my monitor is still at rest

[makai]

when i move the switch all the way over to the right so it shows 220

Yikes! Are you in the United States? If you are, I don't know of any computer that runs at 220 volts. Might just be something I never heard of! Have you always had the power supply set to 220 volts?

[paul_]

yeah im in New York, and no its useally not set to that voltage

[makai]

Set the switch so that 110,115 or 120 is showing (don't know what exactly is on your PSU), then restart your computer. By the way, did you happen to measure the voltages?

Edited by makai, 22 January 2007 - 03:19 PM.

[paul_]

ok so that dident work i made a little video abotu wahst happing at first my psu is on 120v and i try to boot it twice then i switch it around 18 secounds and its now at 220 and i boot and notice everythign stays running but nothing happens at 40 secounds i switch my cmos jumper to the reset position and boot and everythign starts running..

but nothign will load and when i put it back to default same thing happens pwoer for 2 secounds then shuts down

heres the video
http://video.google....197233607066849

[makai]

I just recently repaired a computer for a friend who had the same symptoms. The system would power up and run for only about 2 minutes. His 12v rail was all over the place. I ended up replacing the PSU. The PSU caps were all bulged out.

You really need to find out what your voltages look like. Since it doesn't seem like you have a DMM, enter bios and see if you can find a voltage monitor... it may be under a menu called PC Health. To enter bios, hit the del key continuously after first powering up (before Windows starts booting). Scroll though the menus using the arrow keys.

It is also not advisable to run your PSU at 220v. Normally a 220v line is a combination of 110v phases. I am not sure how a computer PSU will handle your 110 input while it's switched to 220v, but it's safe to say that it's probably not going to work that way.

[paul_]

i cant get into my bios

[makai]

i cant get into my bios

Is the reason because the comp won't stay on long enough?

If it is, then you're going to have to start at the basic troubleshooting stuff. Remove all devices except the PSU, video card, one stick of ram, CPU, monitor, mouse, keyboard. Remove any power connectors from any device like floppies or CDrom drives. Then try powering up again to enter bios to check the voltages.

If that doesn't work, you're going to have to get a DMM, or buy/borrow a PSU to help you troubleshoot. If you have a friend who can loan you a PSU, then borrow it. Just be careful as some systems (such as Dells) have proprietary hardware... in other words, Dell machines cannot use standard ATX power supplies. If your machine is manufactured by an OEM dealer, such as Dell, you may need to contact the manufacture to find out if the PSU is proprietary. Systems can be blown if a wrong PSU is installed.

[paul_]

yeah it wont stay on long enoug,h i have a sepeate psw but it dosent have a lot of wattge maybe 200 max is it possible to run 2 psw at the same time or should i just buy a new one if so what brand do u recommend?

[makai]

I actually don't know if you can run 2 PSUs at the same time. Electrically, you should be able to, however you will need to enable the PSU that is not connected to the motherboard. Personally, I wouldn't do it unless I didn't care about the consequences... and if the original PSU is actually bad, then the test would be mute.

According to your motherboad specs, I don't think you can use the 200w PSU alone either. The manual calls out 350w just for +5volts (heavy load). And, I doubt the 200w PSU has an ATX12V1 connector anyways.

If you really want to purchase a new PSU, then you may want to go with Thermaltake, or Enermax. Personally, I use only Enermax power supplies on all machines I build (550w minimum, dual 12 rail whenever possible). This is just a personal preference with no particular reasoning except that I never had any problems with Enermax. However, keep in mind that without verifying that your PSU is actually bad, purchasing a new PSU may not fix your problem. I strongly recommend getting your hands on a DMM to do some actual measurements before spending well earned dollars.

makai