AMD X2 (939) CPU throttling

[Grimgoth]

I've just reupgraded one of my rigs again from a single core 939 3200+ to a dual core 3800+.
Everything going fine this time, nice temps due to inclusion of a water cooler now. Now, not sure if its the same problem as the stuttering with games I read about digging in the forums, but when I run boinc, it decides every minute or so to throttle down to 20% for about 15 secs, then back up.
Have installed sp3, amd drivers, hotfix, optimiser, regedit, as suggested, but this still happens. This doesn't seem to be a problem if I put boinc on snooze and run games for an hour or two, never notice a throttling. so it seems boinc specific. any ideas?

 

[magman]

Have you got cool and Quiet switched on in the BIOS? I've heard this can clash with some DC programs in some circumstances, this may affect BOINC.

You didn't say which OS you are running, but it might be worth checking the Task Manager to see that both processors are active.

 

[Grimgoth]

well,cool n quiet is off in bios,
windows xp sp3 is what i am running,
both processors are active in task manager
am controlling cpu voltage and behaviour mostly via rmclock.
if via boinc i set processor usage to about 75%- 77.5%, this seems to keep the throttling from happening.