Question I have with this throttling i.e. have a CPU time% setting below 100% is, if the "Leave Application in Memory when preempted" is on or off. Normally it would be irrelevant, unless there is an underlying bug in BOINC itself, not retaining the app in memory during the cool-down phase... at 50% 1 second off, one second on.

Also, is the "While processor usage is less than xx percent (0 means no restriction)" set to zero or some other value?

Personally, if the objective is to have more power to the user rather than running the machine cooler (the objective of the CPU%), I'd only be running the "While processor..." option and set CPU time % to 100.

--//--

Raul, it's better to set the "while..." to zero if it is at 100% to disable the function, as even at that ''logical, give it all'' value BOINC tries to pause the science at times [so observed in past testing] when the system is really busy, then with LAIM off the sciences could unload, IIRC]. BOINC sciences will slow down anyhow to only use all spare cycles. Generally if your systems are 24/7 I'd recommend LAIM on as rush jobs that might come could suspend these tasks, and then revert to last checkpoint when resuming. On DSFL I've seen 1 hour and more at times for the heavy job steps.

Wonder if the chance of WUs getting stuck increases with the length of these tasks [the number of jobs included], or it being pure random to happen, think latter from reports.

--//--

Well, I've been running for almost 24 hours at 100% CPU with not a single stalled task - seems too good to be true. My one PC that is still running at 70% has also not had any stalls, but it's a slower machine and has only run 2 tasks in the past 24 hours. I would say that the problem has been identified - what would you like me to try next?

Well, after running for 8 days without any problems, I reset Boinc preferences to not use more than 90% CPU - guess what, I got a stuck task within an hour. I reset preferences to use 100 CPU, rebooted, and viola - all running well again. I shall continue to run at 100% for as long as possible, unless anyone wants me to try something different.
latakia - I suggest you set Boinc preferences to 'use no more than 100% of the processor', then close everything down and reboot - the task should run again and complete normally, and I dont think you'll get any more stuck tasks as long as you keep running at 100% CPU - watch your PC's temperature.

6.12.33 (both 32 and 64 bit)