Hello,

in my settings I have set to only use 25% of CPUS´s, so one core. But still my machine uses three cores, so I run three WUs in parallel.
This leads to a laggy behaviour of my host. Is the "# of CPU" setting corrupted or is there anything else I am missing? I don´t want to use an app_config.xml if it´s not necessary.

I don't think I have ever seen that, so it is probably something unusual. I would detach from the project, and then reattach. That will recreate some possibly corrupted files.

I don't think it is project-related at all.
Your BOINC client doesn't accept the input or it somehow recognized 12 threads/ cores.

vpf3

The BOINC software controls how many tasks are run, not the project.

Resetting didn´t work. I always thought that the project preferences control how much workunits can be processed.

So what´s exactly the option "Use at most x % of the CPUs" used for?

I know I can control the number of WUs per app_config file, but I thought I can do it via preferences.

So what´s exactly the option "Use at most x % of the CPUs" used for?

That might depend on where you set it.
The BOINC Client has an option to use Web preferences. It should be off by default (on the grounds that mine is off, and I don't recall ever having changed things).
So you set 25% of CPUs in your client.
If you run multiple projects you don't really want to have to go round all projects to set this individually.

Are you using local preferences or global preferences?

In the meantime I found out why my machine was laggy, it was because of an Einstein@home GPU WU, so sorry for the trouble guys :-(

I am still confused about the preferences thing but I will try to understand it somehow.

Thanks all

In global_prefs_override.xml set <max_cpus> to 1%.