Under Tools -> Computing Preferences -> Processor Usage
In the box that says "use at most xxx.xx% of CPU time (0 means no restriction)"

If I set a value of 0%, it should mean no restriction, but in practice it results in a CPU usage of 35-50%. I believe this is a bug - shouldn't no restriction mean that it uses 100% of the CPU?

If I set a value of 100%, the CPU usage goes up to 100% as expected. Note that "use at most xxx% of processors" is also set to 100% in both cases.

System info:
Windows 7 Ultimate 64-bit
BOINC 7.4.42 (x64)
Intel Core i7-4720HQ (4 core with hyperthreading)
Nvidia GTX960M

Running Projects:
Primegrid (CPU)
World Community Grid (CPU)
GPUGrid (Nvidia GPU)
Collatz Conjecture (Intel GPU) - all at once.

The settings means that if -NON BOINC- CPU usage is less than the settings, BOINC will do it's computing according the other preferences. 35-50 percent suggests you have something also in 'Use at most nn% CPU Time'.

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Coelum Non Animum Mutant, Qui Trans Mare Currunt

You're talking about a different setting. The setting you are referring to is the second box from top on the processor usage tab, labelled "while processor usage is less than X percent" - this is not the one I am asking about.

I am asking about the last box on the settings tab - again, the exact label of the field is "use at most X% of CPU time". Setting values of 0 and 100 in that box SHOULD give the same result (since "0 means no restriction" = 100% allowed), but in practice it doesn't - check on your computer and see what I mean.

The texts vary per client version. In mine (0 Means no restriction) only appears with the "While processor usage is less than nn% ;>). In the latest 7.6 test version ** with major reshuffle of preferences the "Use at most nn% of CPU time" has no bracketed text either, instead expanded balloons of what the setting does. No mention of zero = no restriction.

If the processor usage alternates on BOINC processes, then it seems your BOINC is running somehow in a throttled mode. Does your activity menu have 'run based on prefs' selected?

** @Devs, they may want to take note that with 7.6.1, entering 0 in the % CPU time field and saving, upon recall shows 99% as entry. The global_prefs_override file shows though <cpu_usage_limit>100.000000</cpu_usage_limit>

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Coelum Non Animum Mutant, Qui Trans Mare Currunt

After I updated, my machine stopped running BOINC 100%. I wasted a lot of time before I read this thread. It clearly says "use at most ___ % (0 means no restriction) so I should have just guessed and put in 100 anyway, but I doid the whole uninstall/reinstall thing. I hope others read this first. Just type 100 if you want 100, ignore the instructions.

** @Devs, they may want to take note that with 7.6.1, entering 0 in the % CPU time field and saving, upon recall shows 99% as entry. The global_prefs_override file shows though <cpu_usage_limit>100.000000</cpu_usage_limit>

Best update to 7.6.2 then as that's the latest beta.

- I filled in 0 in % of CPUs and got as answer: 16/06/2015 22:36:02 | | Number of usable CPUs has changed from 3 to 4. Which is correct.
- Filling in 0 in % of CPU time shows 100% when returning to the menu. global_prefs_override.xml shows for me &lt;cpu_usage_limit>0.00000000&lt;/cpu_usage_limit>

'0 means no restriction' has been done away with in 7.6.2 and is thus no longer in use.

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Now running 7.6.2 beta on all my computers for several days. No issues to report so far. Glad to see this acknowledged and improved in the new version.

I've been having a problem with scheduling priority (both 7.6.2 and latest stable version). I wonder if I can post it here to save starting a new thread?

I am running the following projects on my desktop PC:
1x or 2x primegrid on GPU
2x collatz on iGPU
8x WCG or primegrid on CPU

All projects have equal resource share 100.

The problem is that the computer has recently stopped requesting and running primegrid tasks on the CPU, and runs only WCG tasks. When I issue an update command manually for primegrid, the event log states "not requesting CPU tasks, not highest priority project".

The Scheduling priority of the two projects are as follows:
Primegrid: -2.32
WCG: -0.15

I've tried using an app_config.xml for WCG with project_max_concurrent set to 4, which should leave 4 CPU cores free for primegrid and whatever CPU the GPU tasks need to run, but BOINC simply runs 4 WCG tasks and the 2 PG tasks I still have in the queue, and refuses to download more PG CPU tasks when I issue the update command, citing the same reason as above.

What is causing this extremely low priority for primegrid? Could it be because the GPU is creating so many points for PrimeGrid? Or does BOINC count those separately? Anything I can do to fix this and run primegrid and WCG equally on CPU (ideally 4 tasks of each simultaneously)?