Ruhnok: How do I do this?
raina: You can right-click the process in the Task Manager and select "Affinity..." to disable/enable cores. This is only temporary but if it works, there are apps to patch your .exe to make the change permanent.
I believe that you can run apps with single core affinity via a custom shortcut. It's something I researched before I got my Vista machine two years ago, though haven't actually tried myself yet as I've not needed to. To cut the instructions down, see the below example:
Create a shortcut with path similar to the following:
C:\Windows\System32\cmd.exe /C START "Tomb Raider" /d "C:\Program Files (x86)\Tomb Raider - Legend" /high /affinity 1 "C:\Program Files (x86)\Tomb Raider - Legend\trl.exe"
This runs a game (in this case Tomb Raider Legend) via the command prompt, with high priority and using the 1st core only.