For a few months, information on the subject of the forthcoming socket AM3+ designed for Bulldozer processors has been clear: socket AM3+ will be compatible with current AM3 processors but it won’t be possible to run an AM3+ processor on an AM3 motherboard.
Moreover, the photos of the socket confirm that there is a mechanical restriction because while the socket notches are in the same place, the one at top right only covers one pin on AM3+ against two on AM3. When you place an AM3 CPU on an AM3+ motherboard, this contact won’t be used and you can’t use an AM3+ CPU on an AM3 board unless you bend the additonal pin round!
Hold your mouse over the image to see a photo of socket AM3+
Strangely, MSI is reported to have told PCG Hardware
that a bios update would make AM3 cards compatible with the Bulldozers, even if functionality would then be limited. This is astonishing, and ASRock has confirmed that the number of pins does imply that AM3 won’t be Bulldozers compatible.
John Fruehe, head of marketing for the Opteron range at AMD, finally confirmed non-compatibility via a message on XtremeSystems
. This puts the nail in the coffin of what was a rather odd rumour.