MacG said:
You'll also need more than 4 gigs of RAM to take advantage of the 64-bit addressing in tiger. Plus you'll need applications written to take advantage of it (and need more than 4 gigs of RAM in their processes).
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Not so....
The G5 processor can only access 2 Gig of memory on a 32 bit OS like Panther(For a single thread).
IF
You have Applications that need more than 2 Gig of memory for a single thread then you need a 64 bit OS to go with your 32/64 bit G5.
The bad thing is unless there are major overhauls to the way the MACH kernel uses memory(specifically the virtual memory manager) then those Applications that need large chunks of memory will still perform rather poorly on OS X.
Also most of Tiger is not 64 bit.... the only part that is 64 bit is for command line POSIX compliant applications. Gui based Apps will all remain and run as 32 bit.
Now that being said while some people are all excited about a 64 bit OS(which as I've just explained Tiger is not), the fact of the matter is some applications will actually perform worse using a 64 bit OS than on a 32 bit OS..... It has to do with the way registers are used.
I personally have many Applications that OS X 10.3 is not suited for and have to use Linux on my Macs to compensate. By the way my testing has shown that Linux out performs OS X for my Apps by more than 25%.
This is entirely do to the way Apple optimized the Memory manager for OS X...... Unfortunatly for me they chose to optimize it for Apps like photoshop and the like. Linux just plain does a much better job overall for me.
Also unfortunatly for me LINUX isnt a very Sexy looking OS like OS X is, but I use it because I need to get my work done in a timely fashion.
I only use Panther on my PBook.