I knew this would bite me as I didnt take note of where I read about it.
I'm pretty sure it was www.xtremesystems.org but I cannot search their site as the picture with the authorisation code you need to type in never appears.

After searching with google and reading everything for about 2 hours, the following make reference to the problem:

http://www.xtremesystems.org/forums/...=175584&page=2
Post 26 mentions it and post 47 a guy has experienced it

http://www.xtremesystems.org/forums/....php?p=2747129
A discussion on the topic.

http://www.xtremesystems.org/forums/...173999&page=24
post 591 and 592 reference 8 to 9 CPUs that are degrading
The last links to a Greek site about the problem but I dunno what it says.

http://www.xtremesystems.org/forums/...173999&page=32
Post 794, this guy can only run at stock speed now.

http://www.xtremesystems.org/forums/...54898&page=141
post 3512 talks about 2 that died.

I'll keep my eye open for the thread that alerted me to the problem, soz I cant find it.