I have an interesting thing noticed on my comp. I've just did a little upgrade on my CPU from AMD Ahtlon 64 3000+ to 3800+. There is Win 7 and Win XP as well on the comp. When I ran CPU-Z in Win 7 it says that the clock multiplier is sometimes x12, sometimes x10 then x9 and x5 and changing all the time, the core frequency or what is stable ~200MHz. I noticed that it changes mostly according to wether CPU is working hard or not. When no program is running and I dont do anything the multiplier is x5,I dont understand this too much, as in the BIOS however there is no option to adjust clock multiplier only the HT multiplier which is x1-x5 max or Auto. However when I ran CPU-Z in Win XP it says the multiplier is x12 and stable regardless a CPU needy program is running or not. I am sorry, but I am a bit noob for this topic, dont know whether this is a big problem or not and I would like to ask your help or advices.
its called cool and quiet on gigabyte boards but its basically just energy saving. you should be able to disable it by going to the advanced cpu features in bios.
the reason its changing in win7 and not in xp is the power plan of the o.s. on win 7 its power saving is on balanced by default on xp you will probably find its set to high performance (its equivalent or even off).
As HEXiT says it is normal operation, when you computer isnt doing anything the CPU slows down (produces less heat, CPU fan makes less noise, and consumes less power), when it has work it speeds back up instantly, no real reason to disable CnQ if you arent overclocking.