[SOLVED] PSU fan will not come on

Cards13 · 10-08-2009, 11:27 PM

So I came home the other day to find my house smelled like an electrical fire and eventually discovered it to be the power supply on my computer. I've now replaced the power supply but the fan won't come on. At first I thought maybe the new power supply was defective so I took it back and exchanged it for another one...same problem. I've plugged in all of the wires exactly as they were from my original power supply. The only difference I can tell from my original power supply to the new replacements is that my original had wires connected to all 20 pins on the motherboard plug and the new ones only have wires running to 19 of the 20 pins...they're missing a white wire. The motherboard is an ASUS K7V if that helps at all.

Please help, any ideas would be greatly appreciated...this is very frustrating.

Thanks,
Mike

**speedster123** · 10-09-2009, 04:49 AM

what supply did you use to replace the burned up one? what video card are you using?

**Tyree** · 10-09-2009, 07:49 AM

Have you tried a different household power receptacle? You can test the PSU out of the case by connecting a case fan to it to present a load.

**simpswr** · 10-09-2009, 08:24 AM

What fan does not come on?

Cards13 · 10-09-2009, 08:36 AM

The new PSU is a Cool Power 500. It's an ASUS video card, not sure of the model number but it's fairly old.

It's the large fan on the bottom of the PSU that doesn't come on. I've read some other posts that said some PSUs have a secondary fan that kicks on as needed, but as far as I can tell this one only has one fan inside.

I'll try another power recepticle but I don't think that could be it because the computer turns on and operates but I have to shut it down after a couple minutes because the PSU gets hot really quickly without the fan running.

**simpswr** · 10-09-2009, 09:48 AM

Many powersupplys use tempreture controlled fans . . it may only come on when the PS needs to be cooled

**Tyree** · 10-09-2009, 10:06 AM

Having only one fan, I would think the fan would operate whenever the PSU is powered on.
I've never encountered one that didn't.

Cards13 · 10-09-2009, 10:15 AM

Could it possibly be due to the white wire (pin #18) that is missing from both of the new PSUs that I've tried? I found a diagram on another website that said it is a -5v lead and is optional...any ideas what it is used for?

Thanks for everyone's advice so far, I really appreciate it.

**Tyree** · 10-09-2009, 11:31 AM

Highly doubtful. The -5V is not used anymore.

Cards13 · 10-09-2009, 08:33 PM

Finally got it working...no idea how though. I swapped my old power cord out for the one that came with my new PSU and plugged it into a surge protector instead of my APC battery backup...and magically it now works. I then switched back to the battery backup and it still works. I also tested the old power cord with a continuity tester and all three wires seem to be working fine. It doesn't make any sense to me at all, but at least it's all working now so I guess that's all that matters.

Thanks for everyone's help and advice!

**simpswr** · 10-10-2009, 07:13 AM

Well done . . thanks for reporting back.

10-08-2009, 11:27 PM	#1 (permalink)
Cards13 Registered User Join Date: Oct 2009 Posts: 4 OS: XP	[SOLVED] PSU fan will not come on So I came home the other day to find my house smelled like an electrical fire and eventually discovered it to be the power supply on my computer. I've now replaced the power supply but the fan won't come on. At first I thought maybe the new power supply was defective so I took it back and exchanged it for another one...same problem. I've plugged in all of the wires exactly as they were from my original power supply. The only difference I can tell from my original power supply to the new replacements is that my original had wires connected to all 20 pins on the motherboard plug and the new ones only have wires running to 19 of the 20 pins...they're missing a white wire. The motherboard is an ASUS K7V if that helps at all. Please help, any ideas would be greatly appreciated...this is very frustrating. Thanks, Mike Last edited by Cards13; 10-08-2009 at 11:33 PM.

10-09-2009, 04:49 AM	#2 (permalink)
speedster123 Mentor Join Date: Oct 2006 Location: United States-New York-Long Island Posts: 5,219 OS: xp pro SP3	Re: PSU fan will not come on what supply did you use to replace the burned up one? what video card are you using? __________________

10-09-2009, 07:49 AM	#3 (permalink)
Tyree Mentor Hardware Team Join Date: May 2009 Location: Illinois Posts: 5,561 OS: XP Pro-7RC-Mandriva My System	Re: PSU fan will not come on Have you tried a different household power receptacle? You can test the PSU out of the case by connecting a case fan to it to present a load. __________________ Posting your PC specs will help us to help you quicker and more efficiently.

10-09-2009, 08:24 AM	#4 (permalink)
simpswr Moderator Hardware Team Join Date: May 2007 Location: Houston, Texas Posts: 12,226 OS: XP, Vista, Win 7	Re: PSU fan will not come on What fan does not come on? __________________ Rich MemTest86 \| BenchTest \| Virus/Trojan/Spyware Help How to post a Screen Shot \| PC running slow?

10-09-2009, 08:36 AM	#5 (permalink)
Cards13 Registered User Join Date: Oct 2009 Posts: 4 OS: XP	Re: PSU fan will not come on The new PSU is a Cool Power 500. It's an ASUS video card, not sure of the model number but it's fairly old. It's the large fan on the bottom of the PSU that doesn't come on. I've read some other posts that said some PSUs have a secondary fan that kicks on as needed, but as far as I can tell this one only has one fan inside. I'll try another power recepticle but I don't think that could be it because the computer turns on and operates but I have to shut it down after a couple minutes because the PSU gets hot really quickly without the fan running.

10-09-2009, 09:48 AM	#6 (permalink)
simpswr Moderator Hardware Team Join Date: May 2007 Location: Houston, Texas Posts: 12,226 OS: XP, Vista, Win 7	Re: PSU fan will not come on Many powersupplys use tempreture controlled fans . . it may only come on when the PS needs to be cooled __________________ Rich MemTest86 \| BenchTest \| Virus/Trojan/Spyware Help How to post a Screen Shot \| PC running slow?

10-09-2009, 10:06 AM	#7 (permalink)
Tyree Mentor Hardware Team Join Date: May 2009 Location: Illinois Posts: 5,561 OS: XP Pro-7RC-Mandriva My System	Re: PSU fan will not come on Having only one fan, I would think the fan would operate whenever the PSU is powered on. I've never encountered one that didn't. __________________ Posting your PC specs will help us to help you quicker and more efficiently.

10-09-2009, 10:15 AM	#8 (permalink)
Cards13 Registered User Join Date: Oct 2009 Posts: 4 OS: XP	Re: PSU fan will not come on Could it possibly be due to the white wire (pin #18) that is missing from both of the new PSUs that I've tried? I found a diagram on another website that said it is a -5v lead and is optional...any ideas what it is used for? Thanks for everyone's advice so far, I really appreciate it.

10-09-2009, 11:31 AM	#9 (permalink)
Tyree Mentor Hardware Team Join Date: May 2009 Location: Illinois Posts: 5,561 OS: XP Pro-7RC-Mandriva My System	Re: PSU fan will not come on Highly doubtful. The -5V is not used anymore. __________________ Posting your PC specs will help us to help you quicker and more efficiently.

10-09-2009, 08:33 PM	#10 (permalink)
Cards13 Registered User Join Date: Oct 2009 Posts: 4 OS: XP	Re: PSU fan will not come on Finally got it working...no idea how though. I swapped my old power cord out for the one that came with my new PSU and plugged it into a surge protector instead of my APC battery backup...and magically it now works. I then switched back to the battery backup and it still works. I also tested the old power cord with a continuity tester and all three wires seem to be working fine. It doesn't make any sense to me at all, but at least it's all working now so I guess that's all that matters. Thanks for everyone's help and advice!

10-10-2009, 07:13 AM	#11 (permalink)
simpswr Moderator Hardware Team Join Date: May 2007 Location: Houston, Texas Posts: 12,226 OS: XP, Vista, Win 7	Re: PSU fan will not come on Well done . . thanks for reporting back. __________________ Rich MemTest86 \| BenchTest \| Virus/Trojan/Spyware Help How to post a Screen Shot \| PC running slow?