Originally Posted by
unclewebb
When you are using the 21X multiplier on a Core i7 920, you are automatically using the turbo mode of the processor.
On the Asus P6T based boards, when you start pushing them too hard, at full load, the multiplier will start to rapidly cycle back and forth from 21X to 20X. This is the Intel design spec but very few motherboards have bothered to follow the Intel guidelines. Some motherboards give you an option to disable this safety feature in the bios but the Asus P6T boards don't have this option which can be a problem for Xtreme enthusiasts.
If you are overclocking your board hard enough and like to see your multiplier locked on 21.0X even when running Prime95 and LinX with the temps going over 80C then you might be a candidate for one of the special bios versions that Asus has been nice enough to release to keep the XS guys happy. It will eliminate turbo throttling at the risk of damaging your CPU or your board. Most guys on XS don't mind a little extra risk if it allows them to run some bigger numbers. That's why this is called XtremeSystems. :yepp:
This was a bigger problem for the original C0 processors since they tended to need more core voltage to remain stable which would lead to turbo throttling sooner.