PC PROCESSORS--is a 64 bit processor twice as fast as a 32 bit? Say they both run at 2.0 GHz.?

Answer 1

Simple answer is no

Answer 2

A 32 bit processor can process 32 bits at a time, a 64 bit processor can process 64 bits at a time, so in theory, it would be twice as fast.
But in real life, you would need about 4 GB of RAM to take full advantage of the capabilities offered by a 64-bit processor. Also, a 64 bit processor only runs 64 bits at a time if the application it is running was designed to do so. This means that if you have a program designed to run in 32 bit mode, it will never run faster than 32 bits at a time. You might see a difference when you are running two programs or more.

But, to make it simple: although it is capable of running at twice the speed, it will probably never do so. It will run faster, but not twice as fast.

Answer 3

Such as adding integers, the speed is the same at 64 bits as 32 bits (but larger numbers are possible). Overall speed gains at 64 bits can be obtained as twice as many CPU registers are available for better optimisation.

On reading integers from RAM, the speed in MB/second is the same at 32 bits and 64 bits. This means that processing the integers can be twice as fast at 32 bits. The programming solution is to only use 64 bit integers when necessary.

With 64 bit working, the original i386/7 floating point instructions are not available and SSE/SSE2 instructions have to be used instead. This is generally faster but can also be slower, depending on the implementation (and compiler).

http://freespace.virgin.net/roy.longbottom/win64.htm