Today AMD launched its sucessor to the Athlon 64 line, named Phenom, at 2.2 and 2.3Ghz.
Phenom is an evolution of the K8 architecture, which itself was an evolution of the K7, the original Athlon. This is not neccesarily a bad thing, if you can evolve a processor to acceptable performance then its definately the better option than a redesign from the ground up.
Having said that the competition, Intel's Core2 architecture, is pretty much a redesign (they started from a Pentium 3, but it is fundamentally different in a lot of places) which is still easily advancing in frequency. AMD is struggling.
Anyway, back to the Phenom. The server line, Barcelona, was released a little while ago. It is produced on AMD's relatively new 65nm process, and has some improvements over the Athlon 64 intended to make performance closer, clock per clock, to Intel's offerings.
There will be several Phenom lines: the 9000 line, signifying quad core, have been released today. The 8000 line has three cores. The Athlon 6000 line will be two core processors. Todays processors are the 9500 and 9600 respectively.
Sounds good so far. But it seems AMD have some problems getting enough speed out of their chips. The inital plan was to launch at 2.7-2.9 Ghz. As you can see from the title, they fell short. A long way short.
To make a long story short (too late) Phenoms are, at best, as good clock per clock as Intel's quad cores. At worst, they're about 70% as fast.
The slowest quad core Intel sells is 2.4Ghz. These sell for about Â£160 today. From a quick search of sites doing Phenom preorders, they look to be falling around Â£150-Â£180.
Not good news. But wait, there's more. The best stable overclock Anandtech managed with their (admittedly engineering sample) Phenom 2.4 was 2.6Ghz. Conversely, Intel's 2.4Ghz quad core 6600 SLACR stepping is ridiculously overclockable, generally hitting upwards of 3.4Ghz.
I try not to be biased in purely technological decisions. I have never bought an Intel processor, initially due to cost, and more recently due to performance of AMD being better. That said, if I were buying now, I would be buying Intel.
Unless AMD manage to scale their processors fast to be competitive next year, there are only two reasons I can see to buy a Phenom:
1. Very tight budget. This assumes the street price will drop to below Intel's slowest Quad cores.
2. Upgrade. If you have a relatively recent Socet AM2 motherboard, you may be able to upgrade to a Phenom.