Remember it's best to use default miner settings, i.e. minermemory 1.
how do you set this in the debug window? i mean directly in the client no external miner
Why do you need debug window? There is the menu item "solo mining on"
Anyway, it's the same as "setgenerate true -1" in the debug window.
because i need to set the number of core, you can't do this with the solo mining on