Obviously, a lot has been written about fan and/or fan power noise in the Bolt. I experienced the issue myself, and found it insanely frustrating. I'm hoping that outlining my steps will help someone with similar issues. I purchased a Bolt VOX 500GB from Amazon in January, and contacted TiVo support about the noise it was making within a few weeks of purchase. The support tech recommended cracking the case open (my first indication that this wasn't going to end well) to see if the fan itself was loose. I did. It wasn't. So I contacted support again and exchanged it for another unit. Same noise issues. At that point I ordered a Noiseblocker BlackSilent Fan XS-2 from Amazon, as prior posters suggested. It fits, but the screw holes don't line up, so I attached it with 3M Command Strips. And the power for the Noiseblocker fan is 3-pin, and the connector on the TiVo board is 2-pin, so you have a 50/50 chance to get it right the first time. It was quieter, but the annoying high-pitched whine was still present, which it turns out was caused by the actual power connection itself (as others have pointed out). I then ordered a USB to 3-pin Power Adapter Cable, and hooked up the fan to a USB port on the TiVo. Dead silent. Running fan. Great. So, to wrap it all up, I Dremeled a hole through the bottom of the case, and routed the power cable through, and put it all back together. I've voided my warranty, but at this point I don't care. It's dead silent and my OCD can relax a bit. I'll monitor operating temperature over the next few weeks, but so far so good (averaging around 55).