Yeah mine did too. The first one I had I think overheated (It was a brand new unit!) so I put a small fan in my second (Brought used) at the end of March 2010.
Here are some photos from 30/03/2010 showing what I did:
http://img32.imageshack.us/img32/3352/dsc01035uw.jpg
http://img560.imageshack.us/img560/4669/dsc01031gr.jpg
Seemed to work great
but I went through about 4 fans from 30/03/2010 till I posted the first post on this thread. Every few months it would start making a funny noise so I eventually added a screw terminal on the end of both cables so I could swap the fans quickly.
The end of the two cables (Red and Black) I soldered directly to the reverse of the DC input to the Unit.
-------------------------------------------------------------------
Downstream Upstream
Connection Speed: 24276 kbps 1211 kbps
Line Attenuation: 16.0 db 6.4 db
Noise Margin: 1.1 db 6.2 db
Telewest (2004-2006): 256Kbps -> 512Kbps
BT (2006 - Present): 8128/448Kbps on 20CN Alcatel DSLAM -> 24276/1211Kbps on 21CN Huawei MSAN
Edited by chris6273 (Sat 17-Nov-12 21:20:18)