Power-draw, plus overclocking
AMD needs to push the underlying K10 architecture to the limit in order to achieve a default 3.6GHz clockspeed. This means that the 975BE isn't particularly frugal when the four cores are running at full chat.
The bottom line here is that the AMD Phenom II X4 975 Black Edition is a decent CPU in its own right, but the improvements made by AMD in the transition to a six-core architecture - the Thuban X6 processors - and might of Intel's new Core 2011 make it look average.
Overclocking
There's not a whole heap of headroom on previous Phenom (Deneb) chips but the 975 Black Edition surprised us by being stable at 4.2GHz (21x200MHz) with only a minor bump in voltage and cooling by way of an Arctic Cooling Freezer 64 Pro heatsink.
Running the multithreaded wPrime and CINEBENCH and throwing in numbers for StarCraft II at the 1,680x1,050 setting, here's how the overclocked chip performs.
There's only so much an increase in frequency can do for an older architecture.
