I was recently asked how to turn off a CPU core in a dual-core computer. Depending on your need, there are actually 3 ways to accomplish it.
The first method disables cores for the whole system. The second turns them off for a specific program. Finally, you may just want to shut off those fake Hyperthreading cores.
Turning off CPU Cores in Windows
This method literally turns off cores in Windows. Just go into msconfig. See the image below.
Solid Tip: Go to Start > Run > msconfig > Boot tab > Advanced options > Number of Processors
Disable Cores for Specific Programs
If you only want to disable cores for a particular application, you can set your “CPU affinity” in task manager.
Solid Tip: Press Ctrl+Alt+Del > Start Task Manager > Processes Tab > right click desired program > Set Affinity
Disable Hyperthreading Cores
An Intel dual-core has 4 “logical” cores and a quad-core has 8 “logical” cores, thanks to Hyperthreading. Most people think Hyperthreading is a joke. It also makes your CPU run hotter, and 99% of users will never see any benefit if it exists.
You can disable these “logical” cores in the mainboard BIOS. This option should be listed as “Hyperthreading [Enabled/Disabled]” in your BIOS options. This is for Intel CPUs only. AMD does not use Hyperthreading (and Hyper Transport has nothing to do with that).