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View Full Version : What is the theoretical 64bit RAM limit?

gigatron
05-23-2005, 07:06 PM
Since 32bit systems can only have 4GB, how much can 64bit systems hold theoretically?

Someone asked me so I was just wondering.
Jonj1611
05-23-2005, 07:13 PM
Up to 128 gigabytes (GB) of RAM and 16 terabytes of virtual memory

Jon
gigatron
05-23-2005, 07:30 PM
thank you :thumbup:
Srek
05-23-2005, 07:42 PM
128 GB is the borderline Microsoft drew for XP Pro 64 Bit. For Advanced Server 2003 it's 1 TB.
The theoretical limit is way higher, 2^64=16.777.216 TB or 16 ExaByte.
Don't expect mainboards that will make use of this any time soon ;)

Cheers
Björn
lots
05-25-2005, 06:11 AM
Also the theoretical limit depends on the CPU. The current 64bit CPUs out there for the x86 architecture do not have 64bit address buses. AMD uses a 40bit while Intel a 36.. Neither of which will get you that 2^64 number mentioned above :)
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