Dell PowerEdge 2950 Server: Quieting the Loud Fans!

Recently we purchased a Dell 2950 III with a DRAC card to investigate adding IPMI support to PA Server Monitor. 

So far it’s great, but what wasn’t so great was the noise.

One blog writes that it sounded like a fleet of jets all taking off at once from an aircraft carrier.  I thought it sounded a little more like an air raid siren I’ve heard on movies, or a tornado siren that we hear around here.  It actually causes ear pain with the case open. 

To be fair, the volume does go down with the case on and after the system takes a few minutes to lower the fan speeds, but it’s still way too loud.

 

So, This Fan Noise is for Real?

After some quick investigation, it became apparent that the bulk of the noise came from the four Dell cooling fans (for reference, fan model number was F126025BU.) 

These things are beasts. 

If they were mounted in the right direction you might think they could lift the server into the air.  Because this server will be in an office environment, a low noise level is a must.  And since it won’t be heavily loaded, cooling capacity isn’t as important.  With that in mind, we bought some quiet consumer-grade fans.  Two things are important when you’re looking at replacement fans:

• The original dimensions of the fan are 60mm x 60mm, so the replacement fans should be the same size.  IIRC, the originals were also 38mm deep, but virtually all replacement fans will be less than that since they don’t have has large a motor, and smaller is OK in this case.
• The replacement fan needs to be a four-pin fan with PWM control.  This is how the motherboard controls and probes the fan’s speed.

 

Small List of Suggested Items and Tools You Might Need

• Replacement Fans
• Band Saw or Hack Saw (to cut plastic)
• Soldering Iron
• Couple Pieces of Solder
• Wire Cutters/Strippers
• Heat Shrink Tubes
• A hot air gun if you have one (like on a rework station), or…
• Lighter/Grill Lighter or Matches
• Plastic Ties/ Computer Wire Ties
• Magnifying Glass and mount (if your eyes require it)

 

DISCLAIMER: We can’t be held responsible for any damage you do to your system! This set of tutorials is not intended for anyone not willing to take a risk of using fans that could possibly cause the server temperatures to get too hot (which obviously could be bad.) This is directed to those who might have these servers in their homes, or small offices where you might not have a server room. It is intended for anyone that might have powered down their servers and stored them away just because they can’t take the noise anymore. If you fit this description, read on.  : )

 

Remove the Fan Bracket

Once you pull the fans out (by lifting on the orange handles), you’ll need to free each original fan from its bracket.  This just takes a little inspection and pressure in the right places.  You should end up with three pieces like this:

 

Making the Cut

With your wire cutters or wire strippers, carefully cut all the wires in one cut (making the cut somewhere in the middle or a bit towards the old fan.)

 

 

The gray connector (bottom right), and the surrounding attached black plastic bracket (not shown here), will be rewired and connected to the new fan (top left). Make sure you strip about a half inch of the plastic off the ends of all of the wires shown below.

 

 

The New Fans, and the Old Fan Seating Don’t Match

Taking a quick step backwards, if you look at the seating where the fan is inserted, you will notice as shown below, there is a ridge of plastic that is necessary to stabilize the fans when they are placed and locked in. You can see this a bit better in the magnified area in the right side of the image (which is also enhanced a bit to point out just where the piece is.)

The new fans do not play well with this plastic ridge and have a protruding side that prevents it from sliding down into place. This is the main reason you’ll need a band saw or hack saw, which we’ll get to here in just a bit.

Please note: NO CUTS are going to be made anywhere on the inside of the server. The cuts will ONLY be made to the new fans before reinserting them into the server.

 

 

In the image below, you can see the final cut on the corner of each fan casing (only to the offending corner of each fan that prevents them from sliding into the server fan slots.)
We’ll discuss how and where to make the cuts next.

 

 

Making Cuts to the Fan Casing to Fit in the Server Fan Housing

Below is a view from the back side of the fan, showing both of the cuts that are needed. Notice we also need a notch cut at the corner closest to the wiring from the fan. We’ll discuss the notch cut more in the next image.

 

 

When the new black outer bracket (containg the gray connector) is placed around the fan, you’ll notice right away the wires will be creased up almost flat against the fan itself (as shown in the image below of a unit that is nearly finished, showing wire placement.) To relieve the pressure and creasing, you’ll need to also cut a notch to allow the wires room to come through.

 

 

This photo shows a little bit better view of how and where you should make the notch cut with your blade saw or hack saw. You may even be able to make all cuts with a Dremel tool, but you’ll have to test that yourself.

 

 

 

Wiring Diagram: Old Fan Connector to the New Fan

IMPORTANT! Matching up the correct wires from the old connector to the new fan is crucial. Seeing as the old fans sound like a fleet of fighter jets, rewiring the fans incorrectly just might cause the universe to implode. So for the sake of civilization, please read this carefully!

Unfortunately, the colors of the wires do not sync up between the two fan parts. And even more unfortunate, the wire colors are not always consistent, even among the exact same models of fans.

To account for this, we have tested to find which wires, according to their connectors, serve what purpose. If you notice, we have grayed out the wire colors intentionally. This is because you should pay no attention to wire colors when connecting. Of course, some will be standard, like black, which will nearly always be the ground wire. But better to be safe and follow the chart below.

Just make sure you match up the wires in the left image (from the old connector) to the wires in the right image (from the new connector that will be discarded), as noted by which spot the wire comes out of the connector. So also make sure you are looking at the connector in the same position as shown below.

 

 

You’re now ready to start soldering the wires together between the old gray connectors and the new fan units. You might want to remove the gray connector from the black plastic bracket until you have all the wires soldered together.

 

Soldering the Wires Together

First, make sure you have a heat shrink tube placed over each wire as noted below (this one happens to be clear, but the tubes in folowing images are light blue) before soldering. Push the tube all way up close to the fan so it doesn’t get in the way.

The ends of each wire should be sort of “frayed.” Leave the wires this way…you don’t want to twist the ends to make them more pointed. You will take the ends of each wire and push them together, so that the “frays” sort of intermesh with each other.

Then, carefully place the soldering iron under the wires at the point where they connect, and gently touch the bare wires for a moment. With the solder wire in the other hand, touch the solder wire to the top side of the connecting wires and quickly melt just a drop or so onto the wire. The picture below should help visualize how to do this.

This may take a little bit of practice before you get the hang of it. Or, you may want an extra set of hands to help if you’re having trouble holding all the pieces together while you try to make the solder.

 

 

Read on to see the final steps “Dell PowerEdge 2950 Server: Quieting the Loud Fans!” – Part 2 >>>