Two new quad-core Phenom II processors, aimed at high-end desktops, will start shipping on Dec. 27, according to retail Web sites. AMD plans to announce the chips next month at the International Consumer Electronics Show to be held in Las Vegas between January 8 and 11.

The quad-core Phenom II chips run at speeds from 2.8GHz to 3GHz and include 8MB of cache. The chips are capable of achieving higher speeds under certain circumstances though. AMD overclocked Phenom II processors to run at up to 4GHz on air-cooled systems, and up to 5GHz on liquid-nitrogen cooling earlier this year.

AMD's Phenom II X4 940 quad-core processor, which runs at 3GHz, is being for US$304 by online computer parts retailer Computers4Sure. The chip is being priced $373 by a Canada-based online retailer, A-Power Computer Online.

Another quad-core processor, the Phenom II X4 920, which runs at 2.8GHz, is being for $271 by Computers4sure. The same chip is being for $317 by A-Power.

For now the chips will support DDR2 memory, but faster DDR3 memory support could be added in a few months. DDR3 provides a larger bandwidth for quicker data transfers between the CPU and memory in PCs compared to DDR2 memory. To support DDR3 memory, AMD will introduce the new AM3 socket for motherboards in the next few months.