PC cpu's have not been clocked past 4.2ghz (they can be overclocked but only if they have been unlocked ie a 3570k is where as a 3550 is not), i remember around 2001/2002 when pentium 4's were being clocked to 3.6ghz however since multiple cores generate more heat with higher clock speeds the clock speeds have remained around the 3.5ghz point on desktop cpus and around 2ghz with mobile cpus.
Current PC build:
Asus Z97I-Plus, i5 4790K @ 4.6ghz, EVGA GTX 980 ACX 2.0 1377/1853/124%, Corsair Vengence Pro 2400mhz 2x 8192mb, Corsair RM850, Corsair H80i, 120GB OCZ Vertex 3 SSD, 750GB Seagate Momentus XT SSHD, 320GB Weston Digital HDD, Corsair 230T, Corsair K50 Raptor, HP XQ500AA mouse, Windows 10 Pro 64bit. iiyama Pro Lite G2773HS 120Hz 1Ms G2G gaming monitor.
