Socket AM3 - Wikipedia, the free encyclopedia
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Compatibility
Socket AM3 breaks compatibility with AM2/AM2+ processors due to a subtle change in key placement. The AM3 socket has 941 pin contacts
[1] while current AM3 processors have only 938 pins.
Tom's Hardware removed the two obstructing key pins from an AM2+ Phenom processor in order to fit it into an AM3 socket. The processor did not work in the AM3 socket, but still worked in an AM2+ socket, suggesting that compatibility issues run deeper than merely the key pins.
[3] It is likely due to the fact that the built-in memory controller in AM2/AM2+ processors only supports DDR2 (unlike AM3 processors, which supports both DDR2 & DDR3 memory).
[4]
As AM3 processors also support DDR2, they are backwards-compatible with Socket AM2/AM2+, contingent upon a
BIOS update for the motherboard. Manufacturers including
Asus,
[5] Gigabyte,
[6] and others have labeled existing AM2/AM2+ boards as being "AM3 Ready" or similar, indicating that BIOS support is provided for the specified boards. This allows existing AM2/AM2+ systems to upgrade the CPU without having to upgrade any other components.
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right on. having loads of ddr2 laying around i sometimes forget :)