Ci7930 2.8 showing 2.0Ghz in Windows7

Hey All, I'm a noob to building so bear with me- 

I'm running a GA-X58A-UD3R with an Intel Ci7930. When I check win7 (64bit) it lists this:

Intel Core i7 CPU 930 @ 2.80gz 2.00Gz.

I assume this is because of a mobo setting (and not some weird things where a 2.8 really means 2.0 unless you overclock)? When I'm in the Bios i can change a setting from 15x (what's it's currently at) to 20x and it goes up to 2.8GZ but my CPU temp goes up. At 2.0 it's runs from 37-42, at 2.8 it goes from 40-67 (i'm using realtemp and intel burn test.). What temp should I run at? Should I invest in another fan/heatsink for my 930? I have a Thermalttaki XCaserVI case with 4 fans.

Thanks!