yes you go to bios to overclock cpu, multiplier x fsb= clock speed, but since you dont even know the basic of overclocking yet, i would suggest researching on google and youtube, theres plenty of tutorials and videos on how to overclock cpu, and its different for every make and model, even same model cpus will have different temp ranges and stable clocks. But its not that hard to go from 2.5ghz to around 3ghz
i recently oc my i7 from stock 2.66ghz to 3.5ghz and was happy with temps and performance, tested it with prime95, temps at idle 35-39C, max while gaming 56C and max with prime95 72C. But i did some more research and decided to lower voltage from stock 1.24V to as low as possible with system being stable, so now im running 3.5ghz @ 1.17V vs stock 2.66ghz @ 1.24V, the result is major performance boost and temps are as low as at stock clock 28-34C at idle, max while gaming 49C and max with prime95 67C. So i gained almost a 1 ghz and only 1-2C of heat, everything is stable after 4 hr of prime95 and inter burn test on standard high and max.
i recently oc my i7 from stock 2.66ghz to 3.5ghz and was happy with temps and performance, tested it with prime95, temps at idle 35-39C, max while gaming 56C and max with prime95 72C. But i did some more research and decided to lower voltage from stock 1.24V to as low as possible with system being stable, so now im running 3.5ghz @ 1.17V vs stock 2.66ghz @ 1.24V, the result is major performance boost and temps are as low as at stock clock 28-34C at idle, max while gaming 49C and max with prime95 67C. So i gained almost a 1 ghz and only 1-2C of heat, everything is stable after 4 hr of prime95 and inter burn test on standard high and max.
Mobo: EVGA X58 SLI LE
CPU: Intel i7 920 C0 @ 4.2 Ghz 1.36v Cogage Arrow
Ram: 3x2GB OCZ Gold 1690 9-9-8-24 1.65v
GPU: MSI GTX580 Lightning @ 970/2200 1.09v+MSI GTX460 Hawk PhysX
HDD: Corsair Force GT 120, 2x F4 320GB Raid 0,F4 2TB, WD-G 1TB
PSU: Corsair HX850 80 PLUS SILVER Modular
Case: Antec 1200 EVGA Mod
CPU: Intel i7 920 C0 @ 4.2 Ghz 1.36v Cogage Arrow
Ram: 3x2GB OCZ Gold 1690 9-9-8-24 1.65v
GPU: MSI GTX580 Lightning @ 970/2200 1.09v+MSI GTX460 Hawk PhysX
HDD: Corsair Force GT 120, 2x F4 320GB Raid 0,F4 2TB, WD-G 1TB
PSU: Corsair HX850 80 PLUS SILVER Modular
Case: Antec 1200 EVGA Mod