The sync thing is mainly on how the memory controller is built, different memory controllers have different charasteristics. Yes you can argue that VIA had memory controllers which showed a very marginal performance improvement when running async with faster memory, however, if you compare the scores vs nforce sync, you will see that for example FSB333/RAM333 on nforce will perform faster than FSB333/RAM400 on VIA on about every benchmark that isn't bottlenecked by some other chipset factor.
The comparison with the AthlonXP is in my opinion very valid because it was the only 'short pipeline' cpu where running memory async was an option and which had a FSB/memcontroller architecture. The A64 is on an inherently different, more modern platform and does NOT have the same issues, yes it does have a short pipeline and a dependence on memory timings, but the memory controller runs at a factor of the full processorspeed, the hypertransport link to the chipset can not be compared to a FSB and doesn't get used at all in cpu/memory communication. The FSB is entirely eliminated from the equation so you don't have async issues, in essence on A64 the memory always runs "in sync".. | 
Intel Core 2: Is high speed memory worth its price?
3rd August 2006, 13:15
