Computers heavily overclocked..Most processors clock frequency is locked,,but there are some which are unlocked..Like 3570(locked) vs 3570k(Unlocked)..The systems which undergo overclocking generate more heat than normal stock PCs,,thus they integrate cooling solutions and extra fans so that the processors does not fry out..
My system incorporates 4 fans and overclocked processor i.e i5 3570k with mobo supporting OCing asrock z77 extreme4..Extra fans improve ventilation and keep both gpu and processor cool..