Only a 3.06ghz of the P4 family supports hyper threading. There is either alot of mislead ppl or alot of scammers who still say lower cpus supoort HT. When I first bought my 2.4ghz P4 from newegg it was suppost to support HT but years later I found out nope. So I upgraded to a 3.06. If you want to see what your cpu specs are, in Yahoo search type in the cpu number (ie SL6S5 specs) the first site is a Intel site with a ton of info on chips. As for turing on HT, it turns its self on from the default settings. It auto detects it. And if a chip with HT is installed, it will auto turn it on as long as the auto is on in your bios. You can check that also. Granted your must also have a mother board that is Hyper Threading ready. If your board doesnt take upto a 3.06 cpu then you can be assured it doesnt support HT. Now as for the half problem... never heard of that myself but Id check the voltage the cpu requires from the site above and check/adjust as need in your bios. Its a common thing to have to set the voltage when putting in a different cpu.