On Task Manager, select processes tab, right click the terminal.exe process, and select "Set Affinity ... ", from there you can see how many core the terminal use. You can also set priority to realtime if you wish.
Better doing this by launching Task Manager with Admin account.
Hope this helps.
Running what ?
Backtesting with MT4 only use 1 core.
Sorry - should of said it is an optimisation process in Strategy Tester.
Surely with the availability of multi-core and multi-processors, this power should be being utilised by such an intensive process as it runs the CPU for over 10 days on each of these machines?
This is one of the limitation of MT4, it use only 1 core for optimization.
Maybe you can check if MT5 is usable for you, it can run all your cores and even those of other computers.