You Reply: The right keystroke to get into the BIOS is DEL. F7 works fine too (you get the boot menu, where you can select the "get into bios" option).
Are you sure your CPU in not throttling due to heat issues? It's fairly common with lattepanda, and it would explain why you CPU gets hogged.
If you want to force your CPU to always stay at the the same speed you could try the free software throttlestop (but ofcourse i'd try from BIOS first). I didn't experiment that much with it to tell you how to use it, but i know its doable.