Key Specs
AM3 (compatible with AM2+)Three
2.8GHz
HyperTransport 3.0
1.5MB
Only weeks after the release of the first Phenom II processors, which were designed for Socket AM2+ systems, AMD has unveiled the Phenom II X3 720 Black Edition chips, which support DDR3 memory and the new Socket AM3. The X3 720, priced at $145, is a 45-nanometer chip with the same architectural improvements as the initial Phenom II chips and a new memory controller that supports both DDR2 and DDR3 RAM.
AMD is taking an interesting approach with the AM3 chips and motherboards. The AM3 Phenom II processors can work on both DDR2-based Socket AM2+ motherboards (a BIOS upgrade may be required) and the new DDR3-based Socket AM3 motherboards. The AM3 socket looks identical to Socket AM2, but it uses two fewer pins; this keeps you from plugging an incompatible Socket AM2+ CPU (which does not support DDR3) into a Socket AM3 board, and it allows AM3 processors to fit both AM2+ and AM3 sockets. If you choose to upgrade to DDR3 memory in the future, you can buy a Socket AM3 processor for your existing AM2+ system and bring the CPU over to a new AM3 system.
The Phenom II X3 720 Black Edition runs at 2.8GHz and features 6MB of shared L3 cache along with 512K of L2 and 128K of L1 cache for each of its three cores. The Black Edition processor's unlocked multiplier makes overclocking easier since you can simply increase the multiplier without having to alter HyperTransport and other settings. Using a stock cooler and the AMD Overdrive software's automatic overclocking feature, we were able to get a stable 3.5GHz out of the processor. Knowledgeable overclockers should be able to tweak even more speed from the CPU.
Final Socket AM3 motherboards weren't available yet (AMD says they'll follow the AM3 processors by a few weeks), so we used a Socket AM2+ Asus M3A78-T motherboard and 1,066MHz DDR2 RAM for our initial testing. We expect even better performance for memory-intensive applications on Socket AM3 boards equipped with 1,333MHz DDR3 memory.
