Originally Posted by bob saget
is there a difference between running 8 instances of pi or 4?
When you have HT off it only runs one thread per core, instead of two. Much cooler temps. By turning HT off I was able to gain 200MHz, and despite the increased clock I dropped 10C or more. If you run only 4 instances with HT on it only shows 50% utilization.
For the most part it seems unless stuff is written with HT in mind it's more marketing than anything. Many multithreaded apps show no performance gain, or decreased performance with HT on. A few show a nice gain, but it's rare.
@ meth, I post the other details when I get some time.