by congo » Sat Feb 23, 2008 10:50 am
There are a few 4000+ models, not sure which one you have, but you could say 2.6ghz for most cores and 2.8ghz for the better ones on stock air.
I have three 3700+ single cored cpu's and they all top out just short of 2.8ghz unless I throw a lot of vcore at them. Up to 2.75ghz, they run cool with low volts (1.45v or under).

Mainboard: Asus P5K-Premium, CPU=Intel E6850 @ x8x450fsb 3.6ghz, RAM: 4gb PC8500 Team Dark, Video: NV8800GT, HDD: 2x1Tb Samsung F3 RAID-0 + 1Tb F3, PSU: Antec 550 Basiq, OS: Win7x64, Display: 24&