I got the same problem. My system is windows 7 64bit ultimate with 8GB ram and a panhom IIx4 955 BE
I use coretemp64 to check my cpu temperature and its always between 50-57 when running games.
Normal i have 30 fps and speed is by 90-100% and then get suddenly down to 15 fps and 20-30%speed for some second.
But when i check my taskmanager i see that the cpu suddenly get up to 100% and then back down 60%
So it cant be the temperatur.
I use coretemp64 to check my cpu temperature and its always between 50-57 when running games.
Normal i have 30 fps and speed is by 90-100% and then get suddenly down to 15 fps and 20-30%speed for some second.
But when i check my taskmanager i see that the cpu suddenly get up to 100% and then back down 60%
So it cant be the temperatur.