The astute among you will have noticed that the 2.6GHz and 1MB of L2 cache per core make the FX-60 effectively a pair of FX-55s on the same CPU, in the same socket, sharing a memory controller and system link to the outside world. That sums it up nicely. While sharing a memory controller and system link will reduce absolute performance compared to two separate 2.6GHz, 1MB chips, we all know how well AMD dual-core processors can run in that situation.
We mentioned earlier that, given the 110W thermal spec, coolers that effectively keep the X2 4800+ happy will be fine with the FX-60. That also extends to coolers designed for FX-55 and FX-57. The 104W and 110W TDPs of those single-core SKUs mean that their own validated thermal solutions will extend to the FX-60. It's nice to see AMD keeping power and heat in check over the last 14 months or so, despite the significant increases in performance.
As to why the FX-60 isn't a 3GHz single-core product, we can but speculate. It's obvious that AMD's 90nm process technology could probably see it debut such a chip at sane voltage and power, likely with the same coolers we've just discussed, using the best core it has available. However, the 3GHz figure raises expectation with the consumer that the company will follow through with the rest of the 3GHz range, on towards 4GHz.
Secondly, the company is moving down the road of hardware multiprocessor and thread-level parallelism in its CPU products, server, workstation and mainstream consumer alike. Multi-core, including AMD's current dual-core processors, are where it's going to be at for the forseeable near to mid-term future.
So it's 200MHz slower than the 2.8GHz single-core Athlon 64 FX-57 in external CPU frequency, but there are two cores. Remember the, 'better'? Exactamundo...
The chips' OPN code, ADAFX60DAA6CD, tells you that it's an Athlon 64 (ADA), FX-60 (FX60), Socket 939 (D), variable-voltage core (A), variable temperature (A), has 2MB total L2 (6), is an E6 revision 'JH' dual-core processor (D). Turning it over to see the 939 pins would show you nothing you haven't seen before.