PSU works but won't stay on

Hello everyone. I have an aging home built computer that contains:

AMD Athlon 64 4000+
Biostar 6100-M9 mobo
Xion 500w (488 combined) single rail PSU
GeForce 8500 GT 256Gib Video Card
4x Patriot 1 Gib DDR 2.7v
Generic DVD-ROM
LG Combo CD/DVD Burner
160G SATA Disk Drive (main)
40G PATA Disk Drive (backup/misc)
Floppy (Yes it still has one)
Currently using Ubuntu Linux 10.4 64-bit

My predicament is one I have not encountered before. Lately it has been shutting down on me and now will not stay on long enough to post. I noticed that it started happening when I mounted my 40G drive (contains backups and movies) and started playing movies it would just die. It wouldn't die if I just browsed the drive and it would only shut down if I tried to access data in bulk (i.e. loading the movie). If I didn't access bulk data then the computer would stay on until I shut it down. Eventually it would just die before post.

I took the PSU out of the pc, opened it, blew it out (it was quite dusty), then hooked it up and checked the voltage levels. It would stay on with nothing connected. I checked the components to see if there was any damage and they looked fine, no burn marks or popped caps no bad odors. One thing that was odd was one of the 4 blue fan LEDs had turned a cyanish color. The 12v rail and and 5v rail were both reading greater than their ratings (12.24, 5.3). Great. So I put it back in the pc hooked up just the mobo no peripherals and turned it on. It stayed on, great. I plugged everything (minus the dvd-rom drive) back in turned it on and it just died after 1-2 sec.

I don't have a spare psu to test however I just ordered a new one to replace it. Anyone have any ideas as to the cause? Not sure if the rail is being overloaded but I don't see how as this computer doesn't do anything intensive anymore (gaming etc.) its just an everyday browse the net play some movies do some programming pc now. (Long winded I know sorry).


EDIT: Correction with psu. Its actually Xion not Xeon.
16 answers Last reply
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  1. Looks like you found the problem by yourself. You are describing a classic PSU failure. They do wear out and fail. When you get your new PSU, you should be fine. If not, come on back and the forum will help.
  2. Thanks COLGeek I had suspected as much but I was hoping I could track the problem and save it. Ah well it happens.
  3. Just a side note. It actually didn't start happening til the power company was messing with our power lines. We have a lot of power problems popping up from time to time (such as someone using a hacksaw on a live transformer to salvage copper, that blew my stereo). I have a feeling that contributed to it as well.
  4. saikou said:
    Just a side note. It actually didn't start happening til the power company was messing with our power lines. We have a lot of power problems popping up from time to time (such as someone using a hacksaw on a live transformer to salvage copper, that blew my stereo). I have a feeling that contributed to it as well.

    That very well could have provided the final nail in the coffin....Been there myself.
  5. Most likely PSU failure.

    That possibility about unstable voltage is also worth considering. An aging electronic component is more vulnerable to voltage spikes. Knowing this, you should utilize power surge protector or an AVR.
  6. I agree with above -- and turning it on repeatedly like that when the PSU was failing is very dangerous, you could have damaged something else.
  7. Thank you all for your input. I received the new psu hooked it up and... Further investigation reveals it was not the psu that was bad. The motherboard finally reached its last moments. After looking it over I noticed some of the caps near the power regulators are bloated. Looks like I'm going to have to break out my soldering iron as this board is very outdated and can't be found. I'm looking right now to see if someone has one in stock but I highly doubt it. I just hope its only the caps that have gone bad. Thank you everyone.

    Please mark as solved.
  8. If you are determined to keep that model of mobo, you can always try eBay for a replacement. Worth a look. I would also suggest a search via Google Shopping (or product search). You might find a "new" "old mobo that way. Good luck!
  9. you can always check out if you want to get your mobo fixed.
    no dont worry im not affiliated with them :)
  10. yeah, if you can solder and have the correct tools, replace the caps, its pretty easy when you know what your doing. If you have to go out and buy a new soldering iron just for this purpose, you may as well just buy a new/ebay motherboard.
  11. I took a few years of electronics so I have all the hardware, just need the components. I already did some massive searching for a replacement but couldn't find anything (it is from 2004-2005 IIRC). I had a thorough look over the mb and six caps are bloated to the point of almost breaking the seals, nothing else looked too bad. I did have a look at, useful info that. I have the caps ordered and am awaiting for them to arrive (from Guess I'll have to use my other rig for a while. Thanks everyone.
  12. lol thecapking. he is the ccompetition. but even though i like a lot i do like free shipping thecapking has!
  13. just make sure the caps are the right size. I ordered caps to repair a psu once but they were all too fat. the psu caps were tall and skinny, and i couldnt find any like that.
  14. Yeah I bought caps that exactly replace the ones on the board. Same ratings and size. I'm pretty paranoid about getting things right the first time when dealing with electronics. I usually triple and quadruple check myself. Don't want to have to re-order. Waiting for a new set would just irritate me more.
  15. Status update. Its 5.30am here and I'm posting from my newly repaired system! All bad caps have been replaced and after reconfiguring the BIOS I am up and fully running! The new caps are rated to withstand 105 degrees celsius and have a low ESR so hopefully the system will last for many more years (even though it is so outdated. Then again so is the C64 and I still use one of those too.). Well as long as nothing else dies. I didn't put the old PSU back in because the case is a pain to remove and install a PSU but I am sure it still works fine. The new PSU is 80 Plus so that's a plus. Thank you all for your time.
  16. Not only do you have a fully functional system now, but you have a backup PSU. Good for you!
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