If it's amd then HT = Hyper Transport. Have no idea what it does, go to wikipedia if u want to know, might find something about the frequencies there too.
Lol, so if I set the HT to say 1X the HTT will be 200Mhz, and if I set it to 5X it will be 1GHz?
Btw "mammikoura" I was readin your sig, just have one question. Why are you going with an XFX 6800GS? XFX is a cheap brand and you really won't be able to overclock or tweak that card much.
you want the FSB X HTT to be as close to 1000 as you can, that will give you a stable system cpu wise. when overclocking try to stay as close to 1000 as you can without going over it