64 bit, 32 bit what does it mean?

  TonyTT 22:08 10 Mar 2006

Input over load,

Having read loads on the subject I must admit to being no nearer actually understanding the difference. I mean if you have a 800 MHZ FSB how does having a more expensive 64 bit CPU make any difference to processing power since the data flow into the CPU is limited by the capacity of the FSB anyway.

How can you optimise the whole system so that one component is not "held back" by the limitations of another?

Help as the whole thing seems to be one data pile up after another.


  hzhzhz 22:17 10 Mar 2006

computers process instructions in binary format. Each bit is capable of processing one binary instruction (zero or one) per clock cycle. Most of the PCs that are currently on the market have 32-bit processors, meaning that they can process 32 binary instructions per clock cycle.

Since 64-bit systems can process twice as many instructions per second as a comparable 32-bit system, 64-bit systems are definitely faster than their 32-bit counterparts. Perhaps the most significant difference between a 32-bit and a 64-bit system is the amount of memory that they support.

The fact that 32-bit systems only have 32-bits of data to work with means that they can only address up to 4 GB of RAM. A 64-bit system on the other hand could theoretically address up to 16 exabytes of RAM (That’s over 16,000,000 GB of RAM). In reality though, there are few, if any, 64-bit systems that support 16 exabytes of RAM. Building a machine that supports that much memory would be extraordinarily expensive. To counter this cost, many manufacturers impose RAM address space limits that fall somewhere between the 4 GB limit of 32-bit machines and the theoretical 16 exabytes that a 64-bit system should be capable of addressing. Most existing 64-bit systems limit physical RAM to somewhere between 8 GB and 256 TB.

  TonyTT 22:29 10 Mar 2006

This is an awsome site for beginnewrs, an answer already.

Hi hzhzhz, so is there no relationship between the speed that the CPU and system RAM can talk to each other through the FSB, and the speed of the overal system. i.e. top of the range 64 bit CPU and bog standard 300MHZ FSB/ motherboard does not effect overall system speed.

  SG Atlantis® 22:56 10 Mar 2006

"the speed of the overal system"

Is dependant on a lot of factors, the FSB speed is one of them. Athlon 64 3700 has an FSB of 200MHz, multiply that by 11 to get the processor speed. The FSB speed is how fast data from the RAM can be tranferred to the CPU to be executed and back.

Other factors in determining the overall system is the kind of RAM, amount of RAM, the hdd type, the graphics card, the processor and the PSU.

Use a slow or dodgy component and it'll bog the system to a crawl.

  DieSse 00:09 11 Mar 2006

32 and 64 bit processors.

32 - means the processor handles data in 32 bit chunks (ie 4 characters at a time)

64 means the processor handles data in 64 bit chunks (ie 8 characters at a time)

If all other factors were ignored a 64 bit processor should be able to throuput twice as much data in a given time as a 32 bit one - of course this is not true in practice, as lots of other design factors affect throughput, including the sofyware. Many 32 bit (internally) processors, for instance, have 64 bit data busses (external connections), and the regular WinXP is a 32 bit OS.

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  Danoh 16:51 11 Mar 2006

What has been covered so far are the benefits of 64bit architecture over 32bit. But there are also benefits in the application layer where the processing "smarts" happens and middle or service layer.

The architectural aspects dealt predominantly with how fast the results of processing can be squirted around the system.
64bit architecture also enables 64bit application processing. This means that more interim results of calculations and decision paths can be stored and reused by application programs, thus speeding up the derivation of the resultant answers. Which then get squirted at the infrastructure to courier to the target device (e.g. your PC monitor).

But even 32bit applications can be run in parallel on 64bit architectures ~ another story though.

  jack 14:32 12 Mar 2006

I bet you wished you never asked!
In essence 64 is the future, but there is not or very little software able to take advange of it - so far
There is a 64 bit XP version around somewhere- but I have heard little of it.

At these levels - to the avarage user it make little difference-.
So if your next purchase is going to be sometime soon
then go for 64 bit, perhaps by the time you are thinking of getting the machine after next there will be some matching software- but dont hold your breath.
PS I rebuilt my machine to 64 bit last year.
Very stable very brisk [what did I say 8-)]

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