Disable Hyper-threading Without BIOS?

I'm attempting to disabled Hyperthreading, but that option isn't in the BIOS. Two guides on disabling the "logical" cores require me to boot up "START" command, but what is that and how do I access it?Disable Hyperthreading in the Windows 7 registry - Super User

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Also, I want to set Team Fortress 2 to not use the HT cores, but the .exe file is non-existent and its files are apparently booted by Steam. I wanted to test if Team Fortress 2 and SimCity 4 (resource hogging singe-core) would improve with HT disabled. I also have an i7 720qm 1.6 GHz, which is the slowest i7 quad-core CPU.I tried to disable four "logical" cores through msconfig, but it also turned off two physical cores as well. I'd rather prefer quad core than dual core with HT.