A total of four different Athlon 64 X2 dual core processors will be available at launch, based on two different 90 nm dies. The Athlon 64 X2 4200+ and 4600+ models sport 512 kB L2 cache per core and run at 2.2 and 2.4 GHz respectively. The 4400+ and 4800+ model numbers run at exactly the same core clock speeds, but have 1 MB of L2 cache per die.

110 Watts TDP

AMD rates the dual core Toledo processors with a thermal design level of up to 110 Watts. This is slightly more than the maximum output of an Athlon 64 FX 55, but should be no problem for any existing Socket 939 motherboard that complies with AMD's specs. All you need to do is download an updated BIOS version that adds Athlon 64 X2 support.

Cool & Quiet & Virus Protection

Two features that have been around since the very first launch of the AMD64 family are Cool & Quiet and the NX (non-execute) bit. Cool & Quiet needs to be supported by the motherboard BIOS, and allows the OS to dynamically reduce the CPU core clock speed in several increments. Windows will automatically take care of this as soon as you change the power profile to Portable/Laptop and install AMD's CPU driver.

Cool & Quiet is particularly attractive as it helps to reduce energy consumption and heat dissipation of the CPU whenever it runs idle or at low load. Please be careful with overclocking ambitions when Cool & Quiet is enabled though. The mechanism will overwrite all CPU multiplier settings you may have chosen manually, returning to the processor default when going back to maximum clock speed.

The NX bit helps to prevent buffer overflow exploits that are typical of many viruses and other attacks. Windows XP requires Service Pack 2 to enable this feature.

X2 Positioning: Between FX And Athlon 64

AMD has clearly stated that the Athlon 64 FX is going to remain the top processor for games and single-threaded applications for the time being. In this context, we expect an Athlon 64 FX 57 at 2.8 GHz to hit the market this summer. Price wise, the Athlon 64 X2 should roughly be between the current FX and the Athlon 64 single core family, with the slower X2 models being somewhat attractive.