My brother in law has a Dell Dimension 8400 which is displaying a warning
message that there is a CPU fan failure, so I advised him to replace it.
However it appears that the fan is powered from a 4 pin header on the
motherboard. I have a few questions that I hope people can help me with.
(a) Is this a pwm fan
(b) Where could he obtain such a 92mm fan - in the UK
(c) Would it work with a 3 pin fan (presumably without pwm temperature control)
(d) Would the bios allow it to boot if it does not recognize that a fan is
connected to the header eg using a fan powered from a molex connecter
Thanks for information on any of the above.
4 Wire Fan Problem (Dell)
Moderators: NeilBlanchard, Ralf Hutter, sthayashi, Lawrence Lee
A 4-pin fan is a PWM fan. The difference between a 3-pin and 4-pin fan is only the 4th pin, which supplies the PWM signal from the motherboard to the fan. 3-pin fans should plug in and work properly into a 4-pin motherboard connector, at least in theory. They are designed to be backwards compatible.
The only caveat is that the 3-pin fan will always run at 100% maximum, and the motherboard will have no ability to control the speed. It will, however, have the ability to measure the RPM, so that should keep the BIOS happy in that respect.
All that said, it really is best to find a 4-pin replacement fan. In the US, we can buy JMC 4-pin fans through the following vendor:
Skyline Graphics
6126 Belgrade Avenue
Dallas, TX 75227
Phone: (214) 388-7922
Email: [email protected]
Internet: http://www.homestead.com/prosites-skyli ... index.html
They might be willing to ship to you in the UK.
The only caveat is that the 3-pin fan will always run at 100% maximum, and the motherboard will have no ability to control the speed. It will, however, have the ability to measure the RPM, so that should keep the BIOS happy in that respect.
All that said, it really is best to find a 4-pin replacement fan. In the US, we can buy JMC 4-pin fans through the following vendor:
Skyline Graphics
6126 Belgrade Avenue
Dallas, TX 75227
Phone: (214) 388-7922
Email: [email protected]
Internet: http://www.homestead.com/prosites-skyli ... index.html
They might be willing to ship to you in the UK.
Frozen CPU and Performance-PCs (both in US) have the JMC 4-pin as well.
Don't know much about Dell Dimesion 8400, but my previous experience with Dell is that they often use proprietary connectors and sometimes even with different wiring scheme. Check that out before plugging anything in it.
Edit: Add another shop where JMC fan is available on-line.
Don't know much about Dell Dimesion 8400, but my previous experience with Dell is that they often use proprietary connectors and sometimes even with different wiring scheme. Check that out before plugging anything in it.
Edit: Add another shop where JMC fan is available on-line.
Last edited by ultraboy on Wed Jun 21, 2006 5:45 am, edited 1 time in total.
I'm not saying this is wrong, but I will say that Dell is one of JMC's largest customers for their 4-wire fans. There exists the possibility that Dell would order JMC fans with a proprietary connection, but I don't see the point of that.ultraboy wrote:Don't know much about Dell Dimesion 8400, but my previous experience with Dell is that they often use proprietary connectors and sometimes even with different wiring scheme. Check that out before plugging anything in it.
-
NeilBlanchard
- Moderator
- Posts: 7681
- Joined: Mon Dec 09, 2002 7:11 pm
- Location: Maynard, MA, Eaarth
- Contact:
Hello Tom,
The point would be that you have to buy whatever parts through Dell. They use(d?) a non-standard ATX plug, that forced you to buy their PS, or their motherboard. They use a proprietary set up on the front panel pins, so that you are forced to buy their case, or their motherboard...sheesh.
The point would be that you have to buy whatever parts through Dell. They use(d?) a non-standard ATX plug, that forced you to buy their PS, or their motherboard. They use a proprietary set up on the front panel pins, so that you are forced to buy their case, or their motherboard...sheesh.
DaveB, this does not mean that you can not use JMC 4-pin fan. It's just that you'll have to check the connector and wiring of the stock Dell fan before plugging the replacement fan in.
If it has a different connector, it's a matter of cutting out pin header(with some wires left) from the old fan and connecting it to your new fan. That's what happened to me with my Dell.
If that still does not work and you're sure that you reconnect the wires as it should be - then it means Dell has used a different wiring scheme as well. Then you'll have to search in Dell Knowledge Base to find their correct wiring scheme, or alternatively do some educated guess by comparing wire colour of the old fan with wire colour of power plug that goes into Hdd - looking at the back of the plug when plugged in - it's 5v Ground Ground and 12v. I had to use this method with my Dell too. Though in your case, you'll have 2 wires left to guess. 
And who knows, you may be lucky and Dell no longer use proprietary connectors and wiring scheme.
If it has a different connector, it's a matter of cutting out pin header(with some wires left) from the old fan and connecting it to your new fan. That's what happened to me with my Dell.
If that still does not work and you're sure that you reconnect the wires as it should be - then it means Dell has used a different wiring scheme as well. Then you'll have to search in Dell Knowledge Base to find their correct wiring scheme, or alternatively do some educated guess by comparing wire colour of the old fan with wire colour of power plug that goes into Hdd - looking at the back of the plug when plugged in - it's 5v Ground Ground and 12v. I had to use this method with my Dell too.
Though in your case, you'll have 2 wires left to guess. And who knows, you may be lucky and Dell no longer use proprietary connectors and wiring scheme.
In the UK you may find JMC fans through Supermicro suppliers - i.e. http://www.boston.co.uk/. Ask for "FAN-0076".