Which program is showing true CPU Speed?

Hi everyone,

My system froze, so I had to reset it. BIOS defaulted to factory values, but I overclocked it again and ran Prime95 stress-test for over 8hrs. So far so good. However, when I check the true speed of my CPU 4 programs are showing 4 different things. See image attached.

My system specs
P5K3 Deluxe
Q6600 2.4 GHz in BIOS OC at 3GHz (428x7)
BFG GT8800 OC2
2GB DDR3
250GB SATA2 System Drive
500GB SATA2 Storage Drive

What's goin' here? Anyone got an explanation?
Prime95 showing 3.85GHz
Core Temp 0.99 showing 3GHz
System Properties showing 3.85GHz
CPU-Z showing:2.5GHz

Lastly, I just opened Core Temp 0.99 and it shows same speed as CPU-Z (428x6). Why did the multiplier go down? i can't seem to figure it out.