Confirming the rumors we heard last week, AMD has officially announced the name of its next-generation processors due out in the second half of this year: Phenom. High-end versions of the chip will be dubbed Phenom FX, vanilla quad-core flavors will be named Phenom X4. These processors will be quad-core only and run at the highest clock speeds in AMD's lineup, much like the current Athlon 64 FX. 

At the top of the product lineup we have the Phenom FX processors (codenamed Agena FX). These processors will be quad-core only and run at the highest clock speeds in AMD's lineup, much like the current Athlon 64 FX. At the Quad FX introduction, AMD indicated that FX processors would be Socket-1207 only, simplifying its product lineup. Unfortunately, AMD has once again reversed its decision and Phenom FX processors will be available in both Socket-1207 and Socket-AM2 flavors.

The Phenom X4 and X2 processors are the sensible versions of the Phenom, these are the ones we will most likely be recommending out of AMD's lineup if history holds true. The X4 and X2 will be Socket-AM2/AM2+ only and are 100% backwards compatible with current AM2 motherboards.  The current Athlon 64 X2 has been renamed to the Athlon X2; given that both AMD and Intel offer 64-bit processors, dropping the 64 from the name makes sense. At the bottom of the list is AMD's Sempron, which is the only single core brand in the product lineup.

Phenom will work in current Socket-AM2/Socket-1207 motherboards with a BIOS update, but it loses the ability to run its north bridge and CPU cores at separate voltages/clock frequencies. If you buy a new Socket-AM2+/Socket-1207+ motherboard, then the CPU cores and north bridge can run at separate voltages/frequencies. The benefit of doing this is not only power savings, but AMD has indicated that it can actually run the north bridge faster than the CPU cores (by 200 - 400MHz) which will improve performance. The L3 cache happens to run on the same voltage plane and at the same frequency as the north bridge, compounding the performance benefits of using a new "plus-socket" motherboard (Socket-AM2+/Socket-1207+). AMD has officially confirmed that Phenom will support up to DDR2-1066, reasserting AMD's commitment to the memory technology it switched to a year ago.