PWM Scythe fan on Dell Motherboard doesnt move!

Jubeidono · Post by **Jubeidono** » Tue May 26, 2009 12:32 am

Well, just like the topic says. We have a very noisy dell server in our lab so I thought i'd change the fans. However the new scythe fans that I put in refuse to move at all! I noticed the current rating is different even though the voltage is the same. Could that be the issue?

There are 3 points on the mobo where fans can be plugged and no matter where I plug the fans in they refuse to move at all. I also connected the scythe fan directly to the PSU and it worked fine. I have included two photos from the fans. I apologise for the bad quality but they were taken with a mobile phone.

Any ideas would be greatly appreciated!

Jubei

Original Fan in Dell Server

Scythe Fan that doesnt move at all:

stromgald · Post by **stromgald** » Tue May 26, 2009 8:29 am

It's not the amperage rating. That just tells you how much current the fan draws, and since it's lower, it shouldn't cause a problem. It's only when the fan has very high amperage, which the motherboard might not handle, that it becomes a problem.

You might want to take pictures of the connectors (on the two fans and the motherboard). Dell sometimes uses custom connectors and if the pins/wires are swapped, it could be why the fan won't start.

Jubeidono · Post by **Jubeidono** » Tue May 26, 2009 8:37 am

Thank you for your reply. Since the colours on the wires were the same, I imagined it should be ok.

i.e. the original fan has Black-Red-Yellow-Blue ,
the Scythe fan has Black-Red-Yellow-Orange

I read on intels site that pin outs between PWM and non-pwm fans are backwards compatible so I assumed the last wire (blue on one fan and Orange on the other fan) is the PWM pin. If dell are doing a different implementation on their mobos then they are not following the standards.

I didnt want to cut wires but now I guess I have no choice.

stromgald · Post by **stromgald** » Tue May 26, 2009 8:59 am

I'm not sure if the connectors are necessarily wrong, but they might be. You also don't need to cut the wires, you can pop them out of the connector with a small needle or screw-driver.

Example: http://www.hardwaresecrets.com/article/496/2

Jubeidono · Post by **Jubeidono** » Fri May 29, 2009 8:27 am

As requested here are the photos of the plugs:

CPU Fan plug. I have removed the plug's receptor plastic shell so that I can plug the scythe fan too. (seen better on next photo)

cpu socket receptor plastic removed. even though 5 pins are shown, the original plug had only 4, last one is not used.

9cm (uppper) and 12cm (lower) front case fan plugs (I have removed the receptor plastic like the cpu only on the upper 9cm fan for now)

plug on the scythe fan (4pins)

It looks like the pinout on the pre-installed fans is different than the scythe fan/standard.

Dell Mobo PWM-Black-Red-Yellow
Scythe Fan PWM-Yellow-Red-Black

Who is going against the standards? Dell or Scythe? or neither? are there any standards for case fan pinouts?^^ there should be right?

Jubei

Nighthog · Post by **Nighthog** » Sat May 30, 2009 3:13 am

Dell has probably gone and switched the wire layout to get DELL exclusive fans. I.E. you can't pop in any fans but but the dell ones. OEM FTW!

Besides. On normal retail motherboards the fan connectors are quite different. Normally only 3 pins for non PWM fan connectors and 4 for pwm capable connectors. They also have a plastic socket which they sit inside.

It's DELL that is at fault. You will surely need to rearrange the cables on your scythe fans to be able to connect them to your DELL computer. Basically you would need to do this whit any fan in this case that you don't get directly from DELL.

Jubeidono · Post by **Jubeidono** » Sat May 30, 2009 3:32 am

Yes I figured that was the case. I rewired the scythe fan plugs and it worked. Damn those Dell servers.

Olle P · Post by **Olle P** » Sat May 30, 2009 6:28 am

Jubeidono.
- The factor three difference in current rating between the fans tells me the original fan is probably more powerful than your suggested replacement.
- The fact that you find it noisy tells me it's not running as slow as might be physically possible, with PWM in action. Either it's not temperature controlled or it needs to run at high speed to keep the system cool enough.
= I wouldn't be surprised if your system goes really hot if you do replace the fan. Keep a keen eye on the temps!

Cheers
Olle

Jubeidono · Post by **Jubeidono** » Sat May 30, 2009 6:34 am

Its a simple web server with 10 hits/day and is idle most of the time. I doubt It 'll warm up. I will keep an eye out on it though! Thank you for the heads up!

PWM Scythe fan on Dell Motherboard doesnt move!

PWM Scythe fan on Dell Motherboard doesnt move!

motherboard socket photos