The big difference make i7 4790K . It has 4.0GHz base clock and 4.4GHz boost clock . But if you have i7 2600K , it is one of the best gaming processors . Another difference 2nd gen i7 suppors PCI-E 2.0 and 1333MHz RAM as standard . But tests show that i7 2600K is a great gaming CPU even though . Moreover , it could be overclocked