to the rescue :-)

The TX and VX chipsets had the 64 MB cacheable area limitation. With any of the newer chipsets, there is no problem like that, even the K6-2 and K6-III are able to cache 4 GB if I remember correctly. The key difference is that the L2 is no longer on the mainboard but integrated into the CPU, that is, the chipset or mainboard do no longer have cache functionality.

With the new AMD CPUs, as far as I know, it is still 4 GB System memory (at least, otherwise, the new boards like those based on the ALi MAGiK1 wouldn't even bother putting in 3 GB system memory capacity.

The main limiting factor nowadays is the operating system. Win9x has a maximum system memory limitation of 820 MB, Win NT goes up to 2 GB and W2K up to 4 GB. Then there are the Linux and Unix systems but I don't know specifics.