There is a bug in Minergate 4.03. In my case (haven't tested other options) I'm merge-mining XDN with MCN and using 2 cores CPU + GPU.
If I close Minergate software directly without pausing mining, after restarting it starts mining automatically as usual, but now it's using 4 cores, even though 2 cores
are chosen in software. It can be fixed by pausing and starting again mining on CPU.
It's minor bug, easily circumvented, but I thought I should let you know.