Fastest CPU in the world?

[Hrithan2020]

Hi everyone,

Just was curious to know,which is the fastest processor in the world in terms of clock speed.AFAIK, using conventional Si-based transistors ur clock speed is pretty much limited.So haven't heard of anything above 5Ghz(not overclocked).
But,it is possible to have much higher clock speed by using other materials(so obviously,not in mainstream market).Something like GaAs based MESFET's?

Any idea,which is the fastest clock speed achieved?

PS:Should be a processor.(Not a single or very few transistor implementation).Else Intel had clocked a single transistor at 293 GhZ!!

[dheeraj_kumar]

IBM Power6 is at 4.7 GHz, and that was like, long back. Its interesting to note that Intel's i7, based on its Nehalem architecture, is at a speed of 2.66-3.2 GHz, having 731mil transistors, while Power6 has 790mil transistors.

[acewin]

jus adding when people can OC e8500/E8600 C2D proccies to 5.4GHz, there would be alot many there in clock terms.
cant be sure.
Power6's name came when I did google for "fastest processor", but as dheeraj said the news was of last year.

[Hrithan2020]

@acewin,
Hasn't E8600 already been overclocked to above 6 Ghz speeds?.(max AFAIK is 6.7 Ghz).But i think the highest ever is P4 3.4Ghz overclocked to nearly 8 Ghz.

But,I'm not talking about mainstream processors.I wanted to know whether there are processors built for niche markets which have much higher clockspeeds(above 10Ghz,most likely not built on conventional CMOS tech),and which was the highest among them.The problem is most supercomputers use "cluster" or "distributed" computing, nowadays.