I upgraded my desktop to the AMD Phenom II X4 620 chip in January for just $99. Today, AMD released a six-core processor starting at $199. From ZDNet:
AMD released today its first six-core processors for desktops, only a few weeks after Intel released its first six-core desktop chip. Unlike Intel’s “Gulftown,” which is available in limited quantities and costs more than $1,000 in retail, AMD’s “Thuban” processors start at around $200. AMD claims computer makers should be able to build complete desktops with Phenom II X6 chips for about the same price as the Core i7-980X Extreme alone.
The two new processors are the 2.8GHz Phenom II X6 1055T, which costs $199, and the 3.2GHz Phenom II X6 1090T Black Edition, which is $295. (With the Black Edition processors, you can overclock not only the CPU, but also other parts of the system, to further boost performance.) In addition to the six-core processor, this new high-end platform includes a supporting chipset, the 890GX, and Radeon HD 5000 series DirectX 11 GPUs. AMD refers to this platform as Leo. The Phenom II X6 can also be used as a drop-in upgrade in any AM2+ or AM3 motherboard.
If you are looking to upgrade soon, consider AMD’s Thuban processors. They can be used with your existing AM2+ or AM3 motherboard. Excellent value for the price.