When AMD introduced the new 940-pin socket AM2 Athlon64
processor to the world, it also effectively retired hundreds of different socket
754/939/940 K8 heatsinks which are not compatible with the new four-post
heatsink retention frame. While physically speaking the AM2 processor is nearly
identical to the previous generations of socket 754, socket 939 and socket 940
AMD K8 processors, the way heatsinks attach to it is different in one very
The socket AM2 processor series uses newly designed
plastic heatsink retention frame that attaches to the motherboard with four
screw holes, to a newly designed four-post metal PCB stiffener backplate. The
new socket AM2 heatsink retention frame and metal backplate are not compatible
with the previous socket 754/939/940 heatsink retention frame and metal back
plates, and vice-versa.
AM2 motherboards will ship with the new AM2 heatsink
retention frame, and that means many existing Athlon64 heatsinks will be
unuseable on the AM2 platform.
All existing K8 heatsinks that screw directly into the
two-post metal backplate of the socket 754/939/940 series are not usable with
the socket AM2 retention module because its four-posts are positioned
differently. Unfortunately, most heatsinks that use this installation method are
the high-end, heavy copper coolers that offer the best performance qualities.
The weight of these expensive enthusiast level heatsinks dictated a firmer
attachment method than the plastic tabs of the old retention frame, and sadly
their useful life is now over.
K8 heatsinks like the Zalman CNPS9500 AM2 and AMD retail AVC Z7U741001 heatsink
that clip onto the socket 754/939/940 heatsink retention frame center tabs will
continue to be compatible with the socket AM2 heatsink retention frame. The
center tabs survived the transition to socket AM2, alongside with a new type of
four-post socket 478-like integrated clip points. Existing K8 heatsinks which
use a cam-lock to apply pressure on the spring clip after it has been attached
to the retention frame tab will also work with AM2 motherboards, though there
are no lock tabs built into the retention cage.
Three tab K8 heatsink clips should also work with AM2,
but it depends on how well the load forces are balanced. Uneven loading is
usually associated with the very inexpensive thermal solutions of lower quality
standards, so if you can avoid this type of heatsink with AM2, we'd recommend
doing that. The socket AM2 standard also introduces Pulse Width Modulation (PWM)
fan speed control, as identified by four-pin fan power cords. For the moment,
both fan and motherboard fan header remain backwards compatible with 3-pin RPM
sensing fan power cables.
Next up, overclocking each of the socket AM2