Intel 875P (Canterwood) Chipset - The New Flagshipby Anand Lal Shimpi on April 14, 2003 6:37 AM EST
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Performance Acceleration Technology
The other aspect of the 875's memory controller that's worth mentioning is what Intel likes to call their Performance Acceleration Technology, or PAT. From the company that came up with terms like Hyper-Threading and NetBurst, you would expect a bit more from the marketing folks instead of "Performance Acceleration Technology" but when are we ever pleased with the marketing guys?
The gist of PAT is that in order to differentiate the 875P from the 865, Intel began speed binning the chipsets and selected the top performing MCHs to be 875P parts with everything else that still qualified ended up being branded as an 865. The benefit of this approach is that Intel can be a bit more aggressive with the memory controller while still ensuring reliable operation. It turns out that these high speed bins are able to shave off, at most, two clocks off every memory access which ends up improving overall performance by a few percent.
Intel's approach to chipset binning is much like the approach they apply to CPU speed binning, which is how they determine what constitutes a 3.0GHz Pentium 4 and a 2.80GHz Pentium 4. With that said, there's no additional logic that must go into enabling PAT, which leads us to believe that in theory, enabling the technology on an 865 motherboard would be possible. Enabling PAT on an 865 would be akin to running a 1.6GHz Pentium 4 at 2.2GHz, meaning that if we were able to enable PAT on an 865 that would be overclocking; whereas PAT on the 875P is a fully validated and supported operating mode. It's not clear whether a motherboard manufacturer would even be able to enable PAT as a BIOS option on 865 chipsets or if Intel has put hardware limitations in place to prevent it from working on anything but the 875P. We'll surely find out in the coming weeks once 865 motherboards are released...