Friday, April 26, 2013

Dell PowerEdge 2950: Silence the Noise, Part 2

First, a thank you to Neil for spurring my renewed energy into finding a solution to the 2950's noise level.  For the background of this project, check out Silence the Noise, Part 1.  In this post, I relate my research findings from my search for suitable fan replacements.

The Fans

To find a suitable replacement, we must first analyze the existing fans so we know the baseline for comparison.  Dell PowerEdge 2950's come with Delta brushless, axial fans in a 60mm x 60mm x 38mm form factor.  Dell appeared to utilize three variants, with Dell-approved replacement part numbers including JC972, PR272, YW880, and DC471.  The ones in my 2950 are JC972, for which the corresponding Delta model number is PFC0612DE.  It should be noted that some sites report the thickness as 35mm instead of 38mm, but according to the spec sheet, the proper thickness to keep in mind is 38mm.

Here's a recap and quick reference for the 2950 fans:

  • Dell Part Numbers: JC972, PR272, YW880, DC471 
  • Delta Part Number: PFC0612DE (I'm sure there are others)
  • Form Factor: 60mm x 60mm x 38mm
  • Air Flow: up to 67.8 CFM
  • RPM: up to 12,000
  • NOISE: 61.5 dB (one fan!!)
  • Voltage: 12V
  • Termination: 4 wire
  • Features: PWM Control
The key elements we need to keep in mind for the replacement are the size (60mm x 60mm), air flow, noise, termination, and features.  

To see like-manufacturer replacements, I checked Delta's website. Delta has a list of currently available fans in a similar form factor if you put in the correct search parameters.  However, in the comments section of the hacking the BMI post, other PowerEdge 2950 owners reported that they swapped the 38mm thickness for thinner fans and they worked fine as long as the replacements had PWM control and a 4-wire termination.  Here are some photos for reference:

Fan Label
4-Pin Connector

Now, if you've read my previous post, you know that I removed two fans leaving me a max of 120 CFM (~63 per fan).  During that time, my CPU temp did not increase above 25 degrees.  That means that across all four replacement candidates I can lower the CFM to 30 CFM max for each fan.  Your mileage may vary.

On arnuschky's blog, in the comments someone reportedly fitted 60mm x 60mm x 25mm fans, so we don't have to stay with the 38mm thickness.  A forum post at provides insight into re-mapping the power pins from different fans into Dell's power connectors.

Keeping that mind, here is a list of potential replacements:

As you can see by visiting the links to these fans, all the power connectors are different with maybe the exception of the last one and would need to be re-pinned.  Also, note that they're all thinner, coming in at a 25mm thickness instead of 38mm.  Instead of trying to re-pin the power connector, I decided to check Delta's list of model numbers to see if they had a fan that I could use to more easily replace the JC972.  To be posted in part 3...

Matthew Matchen Information Security Engineer

In the slightly altered words of Mark Witney, I cyber securify the s*** out of things