32 bit os vs. 64 bit os

[msattler]

Has anybody ever done a direct comparison of 32 bit vs 64 bit crunching?  There are a few who are using the 64 bit that think it is faster, but is it really?  I recall a statement somebody made that the FPU unit in the CPU does most of the actual crunching, so the OS is not in play much at that point.
Is RAM access better in 64 bit, or is that at chipset level in the mobo?
I would consider upgrading my quad rig to 64 bit if I knew there was a definative advantage in doing so, but I don't recall anybody giving it a valid test.

[Devaster]

in 64 bit is used always a flat memory model - all  is in one segment - used short mem pointers - less cpu cycles for memory acess ....
more better when all data are  aligned to 64bit length-bigger in memory   but better  performance (cache prefetch (always complete chache line per cycle for AMD) from memory and cpu-data cache transfers )

[Crunch3r]

Has anybody ever done a direct comparison of 32 bit vs 64 bit crunching?  There are a few who are using the 64 bit that think it is faster, but is it really?  I recall a statement somebody made that the FPU unit in the CPU does most of the actual crunching, so the OS is not in play much at that point.
Is RAM access better in 64 bit, or is that at chipset level in the mobo?
I would consider upgrading my quad rig to 64 bit if I knew there was a definative advantage in doing so, but I don't recall anybody giving it a valid test.

I did that. 64 bit apps are faster but only on AMD cpus.
But you won't see a difference on a EM64T enabled cpu.