More of a CPU Question, then a CPU Problem

Hello Everyone, First time poster ,but long time lurker. I recently built my first PC with info gathered from here, YouTube, and Newegg. Over all the process was pretty simple, so thanks to all the poster that answered my questions before having to ask them. My question concerns the CPU and motherboard, which consist of a intel E8400 3.0 ghz processor and Gigabyte GA-EP45-UD3P MB. When I first boot up and the boot screen appearr's, it show's my MB and CPU, but it shows the E8400 @2.8 GHZ instead of 3.0 ghz. It has shown 3.0 ghz in the past, so I'm not sure why it changed. There's no noticeable performance difference, the worst thing my PC does is hang when I have several apps open (4-5)at the same time. I don't know if the two are related. CPUid and GPUZ both show the processor as E8400 3.0 ghz. I'm more curious as to the why, than frustrated by somethings not right. I'm somewhat aware of intels "speedstep"(?), but I think that would come into play after everything's booted up not at the boot info screen. So thank you for any info you may have.

Thanks flyin, The simplest answer's are always the best. I loaded the defaults and it's back to 3.0 ghz. I still don't know what I did to caused the change. Lesson learned I guess, keep better track of the changes I make.