Bit-Tech published a review of Intel's Core 2 Extreme QX9650 processor

We think it's fair to say that Intel's Penryn architecture can be regarded as a success, as it offers some decent performance enhancements over existing processors, while using much less power in the process. Most of the success can be attributed to the "brute force" methods like the 50 percent larger cache instead of the more delicate features like SSE4, which requires specific optimisation in software to see the benefits. However the most interesting changes should be in the mobile parts which feature some great new technologies.

Specifically, the Core 2 Extreme QX9650 is of course a processor that everyone would love to own, but very few will have the money or need for it. Most of us will want to wait for the mainstream dual- and quad-core 45nm CPUs to arrive, but the Extreme Edition has never been about volume. It's about a technological demonstration that creates a halo effect to help sell the more mainstream-orientated products. I guess you could think of the QX9650 as the Bugatti Veyron of the CPU world - it annihilates everything in its path.

Intel's Core 2 Extreme QX9650 processor Review