From article on new AM2 at anandtech.com Here:
http://anandtech.com/cpuchipsets/showdoc.aspx?i=2688
" It was already clear the new CPU would require DDR2 memory, but it appears AMD is also using this architecture change to upgrade the current mounting scheme for Athlon 64 heatsink/fans. The new design is certainly very secure - more stable than the current design - but there are very few existing heatsink/fans that will work on the new cage. From Socket 754, 940, and 939 the same heatsinks have all worked on all Athlon 64 sockets. With AM2 that compatibility basically ends.
For those buying a retail CPU with the HSF this news won't matter at all. For enthusiasts that have invested in more exotic air, water or phase-change cooling solutions for Athlon 64 this could be important news.
Heatsink, water-cooling, and phase-change designers can make a few changes to existing designs that will allow their products to work with both the new AM2 design and the existing A64 754/940/939 design. Keep in mind, though, that it is not likely your current favorite cooling solution for Athlon 64 can go with you to the new AM2 platform."
http://anandtech.com/cpuchipsets/showdoc.aspx?i=2688
" It was already clear the new CPU would require DDR2 memory, but it appears AMD is also using this architecture change to upgrade the current mounting scheme for Athlon 64 heatsink/fans. The new design is certainly very secure - more stable than the current design - but there are very few existing heatsink/fans that will work on the new cage. From Socket 754, 940, and 939 the same heatsinks have all worked on all Athlon 64 sockets. With AM2 that compatibility basically ends.
For those buying a retail CPU with the HSF this news won't matter at all. For enthusiasts that have invested in more exotic air, water or phase-change cooling solutions for Athlon 64 this could be important news.
Heatsink, water-cooling, and phase-change designers can make a few changes to existing designs that will allow their products to work with both the new AM2 design and the existing A64 754/940/939 design. Keep in mind, though, that it is not likely your current favorite cooling solution for Athlon 64 can go with you to the new AM2 platform."