Strange Psu Problem

[endure]

I have a desktop PC which is quite old but which does what I need. It's old enough that the motherboard has the shorter 20(?) way power socket on it. The PSU fan has become quite noisy and doesn't respond to all the cleaning and WD40 treatment it's been given.

I have 2 spare PSUs - one with the short power plug and one with the more modern (24?) pin plug.

When I try the 24 pin PSU (with it plugged into the correct set of holes) nothing happens at all when I try and turn the PC on.

When I plug the short plug one in the fans in the PSU start spinning fairly quickly although not at full speed. This happens when there is no power connected to the PC at all! It's completely disconnected from the mains supply.

All this has me a bit stumped. Anyone got any idea what's going on?

I could swap the fan out in the old PSU but that would mean digging a soldering iron out and I'd rather just swap PSUs if possible.

cheers

[Satcommlee]

Great post, I plugged in an old PC today and came upstairs to find a keyboard and mouse.. only to hear screams from downstairs that the thing had caught fire.

A half decent PSU for an average PC will set you back about 400 Baht!

[endure]

I wish it was old enough to have a proper switch on the front of the PC rather than a soft switch. At least I could figure out what was going on then. Mind you a machine that old would take 2 hours to boot W8

[rakman]

The 24 pin has 2 yellow and two black wires for the CPU voltage at the "unused" end (when plugged into the 20 pin motherboard. You should have on the 20 pin PSU a second 4 pin connector with 2 yellow and 2 black. You could extract the 4 pins out of the 24 pin connector and move them to the 4 pin connector.

Now the unit that powers up the fans all by itself is a perpetual motion machine and should be used to power the house.

Something very odd there.

[endure]

The 24 pin has 2 yellow and two black wires for the CPU voltage at the "unused" end (when plugged into the 20 pin motherboard. You should have on the 20 pin PSU a second 4 pin connector with 2 yellow and 2 black. You could extract the 4 pins out of the 24 pin connector and move them to the 4 pin connector.

Now the unit that powers up the fans all by itself is a perpetual motion machine and should be used to power the house.

Something very odd there.

Sorry I should have made it clear that I have the separate 4 pin connector on all the PSUs which is plugged into the separate 4 pin socket and which makes no difference to the symptoms I've described.

[reflectionx]

The first 20 pins are the same and your 24 pin PSU is compatible with your mobo. The extra 4 are to provide additional power for PCI Express.

First of all, test your 24 pin PSU using paper clip to see if it's functional:

Disconnect all power supplies cables. Make sure the psu is turned off. Plug the PSU into the wall socket (mains). Insert one end of a paper clip into the green wire pin on the 24 pin power cable connector and the other end of the paper clip into one of the black wire pins near the green wire. That's how the case power switch works. It applies a ground to the green wire. Turn on the power supply. The fan should start. If it doesn't, the PSU is dead.

If the PSU is ok, most likely your mobo is fried. To test the mobo, disconnect everything, remove the RAM. Make sure the PC speaker is connected and turn the working PSU on. Do you hear any beeping codes?

[endure]

Thanks for that. I shall test both spare PSUs.

Perhaps it's not clear from my original post but the PC works OK with the noisy PSU. I'm using it to post this.

It only displays the symptoms I describe with the spare PSUs I try on it.

[reflectionx]

Thanks for that. I shall test both spare PSUs.

Perhaps it's not clear from my original post but the PC works OK with the noisy PSU. I'm using it to post this.

It only displays the symptoms I describe with the spare PSUs I try on it.

if the PSU turns out fine, and your mobo is working with another PSU, you might try to reset the BIOS on the mobo - just disconnect any PSU from the mobo and remove the CMOS battery (although some mobos have the "Clear CMOS" switch or pins (to use with jumper). Also reseat RAM, hdd and other peripherals.

[TommoPhysicist]

Just put in a new fan, no need to solder, just twist the wires together then add insulation tape.

[NanLaew]

20cm 12V DC fans start at about 25 baht at Amorn and IT parts stores. And as Tommo says, just twist the wires together and tape them up. It's all low voltage/current stuff so no worries there.

[manarak]

What is the stated wattage on the PSUs?

Some motherboards will remain dead if the PSU doesn't deliver enough power.

[endure]

Both spare PSUs work with a paper clip.

The PSU that's in the PC is 300w, the spares are 400W and 500W.

Choc block maybe, insulating tape no thanks.

[manarak]

Both spare PSUs work with a paper clip.

The PSU that's in the PC is 300w, the spares are 400W and 500W.

Choc block maybe, insulating tape no thanks.

hmmm.... very odd.

300W is nowadays really weak for powering a PC, maybe it is noisy because it runs at or past the limit.

Maybe you could try to put a clip into the "unused" end of the 24 pin connector, between the +5 and ground?

[endure]

Both spare PSUs work with a paper clip.

The PSU that's in the PC is 300w, the spares are 400W and 500W.

Choc block maybe, insulating tape no thanks.

hmmm.... very odd.

300W is nowadays really weak for powering a PC, maybe it is noisy because it runs at or past the limit.

Maybe you could try to put a clip into the "unused" end of the 24 pin connector, between the +5 and ground?

It's been running quietly for a couple of years. Just became noisy over the past couple of days.

[manarak]

Both spare PSUs work with a paper clip.

The PSU that's in the PC is 300w, the spares are 400W and 500W.

Choc block maybe, insulating tape no thanks.

hmmm.... very odd.

300W is nowadays really weak for powering a PC, maybe it is noisy because it runs at or past the limit.

Maybe you could try to put a clip into the "unused" end of the 24 pin connector, between the +5 and ground?

It's been running quietly for a couple of years. Just became noisy over the past couple of days.

check if there aren't some hairs or dust wrapped around the fan's axis. a small drop of (precision machine) oil on the axis can also work wonders

[jayceebee]

Beware, I had similar issues with a brand new ATX PSU, took it back to the store where it was replaced, same problem and they were adamant it was OK even showing me it running in another PC chassis. The particular brand I tried ran the fans but would give no display. Eventually it was found that the problem PSU's did not have a -ve 12 volt supply, some older motherboards will not work without it. Not all replacements are to the original specification.

Edited January 20, 2013 by jayceebee

[reflectionx]

Both spare PSUs work with a paper clip.

The PSU that's in the PC is 300w, the spares are 400W and 500W.

Choc block maybe, insulating tape no thanks.

If you had a multimeter you would be able to further test both PSUs, but I doubt both would be defective at the same time. Did you try to reset the CMOS an re-seat all the components?

Also, what is your mobo model? A firmware upgrade (if available) might solve such issue.

[NanLaew]

Holy sh!t!!! BIOS upgrades, memory card reseats.... all for a noisy PSU fan?

I try and avoid using WD40 on these fans as there's too much plastic around these tiny bearings to get any lube on the dodgy bits; WD40 isn't friendly with all plastics. For PM, once a year, get an aerosol duster and blow out all the fans, more frequent if you have a really dusty environment such as carpets near a floor-mounted PC.

[JakeBKK]

you could use a post - card , if you are not sure that the output is correct. The fans inside you psu are standard 12v 80mm fans. So open it up , unscrew the old one and put a new one in.

[reflectionx]

Holy sh!t!!! BIOS upgrades, memory card reseats.... all for a noisy PSU fan?

I try and avoid using WD40 on these fans as there's too much plastic around these tiny bearings to get any lube on the dodgy bits; WD40 isn't friendly with all plastics. For PM, once a year, get an aerosol duster and blow out all the fans, more frequent if you have a really dusty environment such as carpets near a floor-mounted PC.

First of all, FW upgrade is something to be be done regardless if one has issues or not. It might improve performance and stability and will add support for newer devices, etc ... Following your logic - patching OS, apps all for some malware? ...

Anyone with a little above average experience would tell you that failed fan = fired PSU = possibly fried mobo. I've seen plenty of these. Just because someone has assembled 1 or 2 PCs at home does not make them experts, duh!

Op has 2 spare PSUs, he just can get them to work. Re-seating RAM takes 5 seconds. Clear CMOS = 1 minute. Fried mobo = $$$ for a replacement, 5 mins to replace, possible need to reinstall Win to rebuild the HAL, etc etc ...

[NanLaew]

Holy sh!t!!! BIOS upgrades, memory card reseats.... all for a noisy PSU fan?

I try and avoid using WD40 on these fans as there's too much plastic around these tiny bearings to get any lube on the dodgy bits; WD40 isn't friendly with all plastics. For PM, once a year, get an aerosol duster and blow out all the fans, more frequent if you have a really dusty environment such as carpets near a floor-mounted PC.

First of all, FW upgrade is something to be be done regardless if one has issues or not. It might improve performance and stability and will add support for newer devices, etc ... Following your logic - patching OS, apps all for some malware? ...

Anyone with a little above average experience would tell you that failed fan = fired PSU = possibly fried mobo. I've seen plenty of these. Just because someone has assembled 1 or 2 PCs at home does not make them experts, duh!

Op has 2 spare PSUs, he just can get them to work. Re-seating RAM takes 5 seconds. Clear CMOS = 1 minute. Fried mobo = $$$ for a replacement, 5 mins to replace, possible need to reinstall Win to rebuild the HAL, etc etc ...

Read the OP <deleted>. What malware?! The old PC is working fine, only the PSU fan has gotten noisy. The OP has a couple of other PSU's that he is trying to substitute in lieu of replacing a 30 baht fan but IMHO, is on a hiding for nothing since it's a LEGACY mobo and PSU he is dealing with. Easier to take out the noisy PSU, replace the fan, put it back in and carry on. I am not the one recommending BIOS upgrades, software upgrades and hardware reseats... and I have only built about 40-odd PC's and a couple of laptops. If it aint f*cked, why <deleted> with it?

I mean, when you need a new tire on the car, do you replace the piston rings at the same time?

[JSixpack]

I try and avoid using WD40 on these fans as there's too much plastic around these tiny bearings to get any lube on the dodgy bits; WD40 isn't friendly with all plastics.

Nobody suggested WD40. manarak suggest a drop of machine oil on the axis; that was good advice and it might do the trick. So you peel back the cover in the center and apply.

Funny the tangents this thread took w/ a perfectly clear simple problem.

Edited January 21, 2013 by JSixpack

[BlackPuddingBertha]

Nobody suggested WD40.

The OP did in the first post.

WD40 is NOT a product that should be used on electronic equipment. Keep it for your car.

[JSixpack]

Nobody suggested WD40.

The OP did in the first post.

WD40 is NOT a product that should be used on electronic equipment. Keep it for your car.

Ha! Guess that was so inconceivable it blew right past me!

Couple of tutorials on the lube route:

http://www.ehow.com/...r-case-fan.html

http://www.overclock...ricate-pc-fans/

Replacing the fan:

http://www.instructa...an-Replacement/

I wouldn't replace the fan with just any old fan you can find in Amorn or lying around in boxes at Tukcom back end shops. I'd be sure to get a name brand known for a low noise level, such as a Scythe. The better shops at Tukcom sell such.

[NanLaew]

....

I wouldn't replace the fan with just any old fan you can find in Amorn or lying around in boxes at Tukcom back end shops. I'd be sure to get a name brand known for a low noise level, such as a Scythe. The better shops at Tukcom sell such.

Yeah, way to go. Get a 500 baht fan for a 300 baht PSU.

Mind you, today I saw some 12,000 baht low-profile tires on some awesome 50,000 baht alloy rims getting fitted to an old 150,000 baht Toyota Tiger. Wasn't yours was it?

[BlackPuddingBertha]

Get a 500 baht fan for a 300 baht PSU.

When you next see a working PSU on sale for 300B, please let us know.

[jbrain]

Get a 500 baht fan for a 300 baht PSU.

When you next see a working PSU on sale for 300B, please let us know.

http://www.jib.co.th/web/index.php/product/readProduct/10125/6/index.html

[endure]

Fixed it. I found a very old PSU - a hybrid with both the 20 way and the previous standard connector on it. Stuck it in and it worked first time. Very quite and much better quality than the noisy one.

[JSixpack]

....

I wouldn't replace the fan with just any old fan you can find in Amorn or lying around in boxes at Tukcom back end shops. I'd be sure to get a name brand known for a low noise level, such as a Scythe. The better shops at Tukcom sell such.

Yeah, way to go. Get a 500 baht fan for a 300 baht PSU.

Exactly. A cheap fan can be about as noisy as the one replaced. That's why there's a large market for high quality quiet fans. The practical goal is to end the noise and be sure it's ended once & for all. It's not about decoration and "pimp my PSU." If the fan outlasts the PSU board, it can be removed and used in a case or another PSU.

[BlackPuddingBertha]

When you next see a working PSU on sale for 300B, please let us know.

http://www.jib.co.th...25/6/index.html

Crikey. What's the MTBF measured in? Minutes?