That was a PERFECT explanation! :smile:

(I haven't seen any performance drop running 1 instance of Prime95 on a HT CPU... No program is 100% optimised so there are always a few cycles left over... I figure those few extra cycles can be put to use for general OS usage so the main Prime95 instance continues to run 100%!)

Great email, explains it well.

Turned HT off and my iteration times change slightly, from 0.051 to 0.050

(Sorry about the question, i thought I had already turned HT off after reading the previous answers)

Jim

Maybe you could use affinity or something on hyperthreading. I don't know much about it but it seems kinda like dual processor.