64-bit Windows

What does 32-bit and 64-bit mean?

The terms 32- and 64-bit refer to the maximum number of ‘bits' - a bit being a single unit of data - that a computer can process at any one time. Computers use RAM (random access memory) to perform the functions necessary to run software programs.

A computer built on 32-bit architecture can access less RAM than one on 64-bit architecture. The demands of today's software applications mean that we are currently pushing 32-bit systems to their limits, but 64-bit architecture allows us to build computers with the power to deal with much more complicated tasks.

Until recently, 64-bit versions of Windows XP and Vista were rare. But when Microsoft unveiled its new Windows OS, things moved on and many new PCs have 64-bit Windows 7 pre-installed. Windows 7 retail boxes contain a choice of 32-bit and 64-bit editions.

What are the limitations of 32-bit Windows?

The theoretical maximum amount of memory that can be accessed by 32-bit software is 4GB. However, many components inside a PC, such as the video card, are accessed through memory locations and so 1GB of the 4GB is reserved for them.

This means that no matter how much memory is installed in the PC, a 32-bit Windows installation can only use the first 3GB. When Windows runs short of memory, it can use the hard disk as temporary storage, but this is much slower to access and, therefore, the computer slows down.

As software becomes more complex, it makes more demands on the computer's memory and 32-bit Windows PCs will struggle to cope.

What is the advantage of 64-bit Windows?

The theoretical memory limit of a 64-bit program is 16.8 thousand million gigabytes but, since you would need a motherboard the size of a football pitch to fit that much RAM, in practice 64-bit Windows 7 limits the memory to 16GB in the Home Premium edition and 192GB in the Professional edition.

The more memory that Windows has available to it, the faster it runs, so 64-bit Windows is potentially much quicker than 32-bit.

You do need to install more than 4GB of RAM to get the full benefit, but there are advantages even with just 4GB because none of this is reserved for memory-mapped components like the video card.

Can I install more than 4GB of memory?

The amount of memory that can be installed in a computer depends on its design. Many older PCs are only designed to accommodate 4GB of memory at most.

They generally don't have enough sockets, or you can only install memory modules with limited capacities. New PCs are usually designed to accept more memory and bigger modules, so the physical limit is higher.

It will depend on the PC though, so use either the System Scanner or the Memory Advisor on the Crucial website to see how much the motherboard can take. You may find that the motherboard in your PC is limited to 8GB, but that is more than adequate for today's software, 64-bit or otherwise.

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