On May 4, 2006, at 1:25 PM, Kep Woof wrote:
Sure. For the most part, if you don't have more than 4GB of RAM,
there is little point to running in 64-bit mode. A more fine-grained
analysis:
I think I get it now.. having seen loads of adverts and hype
(particularly from apple) bigging up 64bit, I think i misunderstood
(or never bothered to try to understand more likely). I thought it
meant the bus (or something like that - i obviously know very little
about hardware) was twice as wide and so twice as much data could go
through at once, so it was similar to being twice as fast, or
something like that(!).
This impression is partially true, but the subject is complicated.
The AMD64 or Intel EM64T platforms do have a better bus, in the case
of AMD, HyperTransport is a fairly new and fast backplane which is 16-
bits wide at a nominal 1000MHz bus speed, not 64-bits wide or
anything like that. The older 32-bit AMD or Intel platforms tended
to have a 400-to-533 MHz FSB & memory bus (Intel's "quad-port
architecture", VIA's quad-pumped V-link, etc), and the newer 64-bit
Intels are 800MHz FSB mostly w/ 533MHz DDR2 memory bus.
Are you saying that it just means you can address more memory?
No, the CPU registers and the address bus can be wider (not just the
memory bus) with Intel EM64T or AMD64 architectures, and can get more
work done per clock for some tasks, but can also be slower for some
common tasks, too.
Again, if you have more than 4GB of RAM, using the CPU in native 64-
bit mode is probably the way to go; if you've got less, using the CPU
in 32-bit mode might very well work better, but it really depends
upon the type of processes you run.
--
-Chuck
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