SOLVED AMD is heading in the right direction

[azanimefan]

If anything, it's the other way around. I have an AM3 PII in an am3+ board.

yep. you'll see that with AM3+ assuming the bios supports the cpu. This is in large part due to the change in AM3 to AM3+ being intended to be smouth and seemless. the same was the case with AM2 to AM2+... though AM2/AM2+ cpus cannot and will not work in AM3 mbs... AM3 cpus CAN work in AM2/AM2+ MBs... (sidenote, the main difference from AM2/AM2+ and AM3 is AM3 utilizes DDR3 ram... we can assume a further socket change to AM4 when DDR4 becomes the ram of choice, and a similar compatibility step as we saw with AM2 to AM3)

 

[Bobnova]

Last Athlon XP was a single core on Socket 754. That was only a three-chip run too. All the other Athlon XPs were s462. There were no XP dual cores.
By the time AM2 rolled around it was Orleans (single core) and Windsor (dual core) K8 stuff.

Socket 775 had P4 90nm, P4 65nm, P4 dual core, core2 65nm, core2 45nm, core2quad 65nm, core2quad 45nm. That's one massive architectural change and six total changes. Oh and a 90nm P4 works fine in a top end late model X48 chipset motherboard.
lga1366 got two generations, big difference between 'em too.
LGA1156 got screwed (see: AMD s754).
LGA1155 has had two generations.

The only place I have to really hand it to AMD compatibility wise is heatsinks, S754 onward fits for the most part. AM2 and onward is all identical. That's awesome.

 

[rescuetoaster]

That is awesome, and was a pleasant surprise when I went from 939 to my current rig. My nice zalmann that I bought in 2007 popped right on.

 

[azanimefan]

Last Athlon XP was a single core on Socket 754. That was only a three-chip run too. All the other Athlon XPs were s462. There were no XP dual cores.

you're right, i was thinking about the Athlon 64 x2 which were on AM2 mbs... that you can stick certain PhII x4 cpus into a MB built for an old old Athlon 64 x2 is impressive to me.