Re: Fan for Thermaltake ultra 120 extreme.
I would suggest a Yate Loon high speed fan. I'm sure you can find them somewhere in the UK. I got a Yate Loon Medium. I think it's about 1200rpm or something like that.
It's fairly slow, but it keeps the CPU cool enough, and it is close to silent. I don't overclock though. If I was to overclock, I would get the faster Yate Loon.
The Sharkoon 2000 is probably a good choice too. I use the Sharkoon 1000's as case fans, and they are great, and I've heard that the 2000's are good too.
Re: Fan for Thermaltake ultra 120 extreme.
Got a Scythe S-Flex 1200 on mine, which does the job pretty well. Haven't really overclocked it yet though, so you may want the 1600 version. The Scythe Slip Streams may also be worth considering, quoted specs (comparing Scythes own between models, which should hopefully be comparbale if not entirely accurate!) make them a little bit noisier thanthe S-Flex but they push more air, for a given rpm. Seem to be quite well recieved on SPCR as well. Yate Loons are great for the price though.
Re: Fan for Thermaltake ultra 120 extreme.
i'd probably use an Antec Tri-cool on it. That said, i'm not very knowledgable on the subject of fans.
Re: Fan for Thermaltake ultra 120 extreme.
Yate Loon medium speed... very good fans.