Here is a shot of the inside of the case before I remove the old 120mm fan. The front left top place is the fan holder. So I only have to remove two screws and it's out.

The old fan is getting retired with a swift toss into the trash can.

Now that the old one is gone it's time to place the new one into the holder. In my case, I had to make sure none of the blades would touch the holder. 

With everything back together, I turned the rackmount case back on. No sound, did I forget to plug the fan in? So I took a look and the blue glow was shining through the fan filter. I guess the noise level wasn't a joke. I did notice the glow behind the air filter looked much better than without the filter.

Here's without the filter, seems the light just isn't as smooth.

Overall the Aerocool Turbine Fan is quite a deal at $15. Combine that with the air flow and low noise level, this is a great replacement to pick up.