The AMD Athlon 1266 was a desktop processor with 1 core, launched in March 2001. It is part of the Athlon Model 4 lineup, using the Thunderbird C architecture with Socket A. Athlon 1266 has 256 KB of L2 cache and operates at 1266 MHz. AMD is making the Athlon 1266 on a 180 nm production node using 37 million transistors. The multiplier is locked on Athlon 1266, which limits its overclocking potential.
With a TDP of 66 W, the Athlon 1266 consumes typical power levels for a modern PC. AMD's processor supports DDR1 memory with a single-channel interface. The highest officially supported memory speed is 266 MT/s, but with overclocking (and the right memory modules) you can go even higher. Actual memory technology support depends on the chosen motherboard, because the memory controller is located on the motherboard (not in the processor). Although the processor doesn't come with integrated graphics, certain motherboards with compatible chipsets can provide this capability.
A lot of games will not work on this processor, because they require the SSE instruction set, which is not supported.