What Does 64-Bit Mean In Relation To Your PC, Software & OS?

CG Director Author Christopher Harperby Christopher Harper   /  Published 

What does 64-bit mean in relation to your PC, its operating system, and the software you’re running?

For this to make sense, we’ll need to talk about some fundamental operations happening within your PC.

Let’s dive into what you need to know, including what a “bit” actually is, so we can establish what actually makes 64-bit so important.

What is a Bit in a PC?

Bit stands for “binary digit” and is the simplest form of data that can be stored or read by any device.

As the name suggests, binary digits can only have 1 of two possible values. You can call them 1 and 0, on and off, or even yes and no. But it all boils down to the same idea – only two possible values.

These bits have to be stored somewhere, and your PC’s RAM (Random Access Memory / System Memory) consists of billions of microscopic, so-called, capacitors, that can each store one bit. And those billions of bits make up Gigabytes of capacities that we’re used to today.

This is why RAM is one of the components that’s most sensitive to supply chain disruptions: manufacturing chips that house billions of these Integrated Circuits (ICs) aren’t cheap, and not every facility can handle them.

Those are just two values a bit can represent.

But what if you need more options? Well, the great thing is, you can string bits together pretty much indefinitely.

With two bits you’d already have 4 possible values; with 3 bits 8 possible values, etc.

Two to the power of the number of bits. 2^(# of bits) equals the number of possible values the string of bits can represent.

Now let’s move on:

What Does 32-Bit mean?

So, with a basic understanding of Bits in place, what does 32-bit even mean? If your desktop/laptop CPU isn’t 64-bit, it’s probably 32-bit.

The most prominent 32-bit architecture is the 32-bit x86 desktop CPU architecture, which you may recognize as the baseline for almost every Windows PC ever.

However, most modern desktops are actually using x86-64 CPUs…which I’ll explain in a little bit.

Memory (RAM) Limitation on x86 32-Bit CPU

For now, what you need to know about a proper 32-bit CPU, especially an x86 one, is that you will be limited to 4 GB of RAM, in total.

To be exact, you’ll be limited to the total number of address spaces available to, well, address. In a 32-bit system, you can have 2^32 address spaces or bytes, which equals 4.294.967.296 bytes. Quickly convert this to GiB, and you get an exact 4 GiB number as the maximum possible number.

(Please note GiB and GB aren’t the same. Our TiB vs. TB article goes into more detail about this).

Considering that having that much RAM wasn’t commonplace until the late 2000s and 32-bit CPUs debuted in the era where a single gigabyte of RAM would have been massive overkill, it makes sense that this limit didn’t seem problematic at the time.

If you’re wondering why 32-bit processors are limited to 4 GB RAM, there’s no way to avoid diving into a bit of computer architecture to explain – so roll up your sleeves!

Explaining x-Bit Processors and Why Memory Limits Come Into Play

To make things easier to understand, I’ll grossly oversimplify this next part.

In your PC’s RAM (Random Access Memory), each bit is stored in a capacitor, which is accompanied by its own transistor. In essence, bits are represented by whether or not there is an electric charge in a capacitor (0 or 1, on or off).

Groups of 8 of these capacitors + transistors make up your RAM storage and can store 1 byte of data each (8 bits = 1 byte). However, your CPU needs the addresses of these chunks to read data from them effectively. This is called a memory address and has to be unique for each aforementioned ‘group.’

Let’s say we have a 2-bit CPU. What does this mean? Well, it basically means that the longest sequence that this processor can handle is 2 bits long. So, if it wants to read memory addresses, the only unique address options for it would be 00, 01, 10, and 11.

This puts a hard cap on how much memory this processor can handle, which in this case, is 4 bytes for a 2-bit processor.

So, the max number of ‘byte addresses’ that a CPU can handle depends on the length of sequences it can read at once. As you must’ve now realized, for a 32-bit processor, this means that the CPU can read 32-bit sequences at a single time.

Phew! Still with me? Okay, now if memory addresses can be 32 bits long, you end up with 2^32 possible address combinations. This number is 4,294,967,296 total possible addresses, which means that the CPU can’t handle more than 4,294,967,296 bytes of memory.

So, let’s convert that into Gibibytes, shall we?

Byte to Bits conversion

Well, that’s how you get your 4GB max limit. Anything over these many bytes just can’t be addressed, and your 32-bit processor has no way of identifying or accessing them.

So, once we ran into that hard limit introduced by 32-bit CPUs and operating systems, we moved on to 64-bit CPUs and operating systems. Technically, most of the world moved onto x86-64 CPUs.

What Does 64-Bit mean?

A 64-bit CPU is a processor that can handle instructions in chunks of 64 bits. So, if we use our above formula to calculate the maximum address space for a 64-bit system (2^64), the number might surprise you. 

64-bit Max Memory calculation

Its theoretical memory limit has yet to be reached on a modern motherboard, but would, in theory, be capable of hosting up to 18.4 Exabytes (16 Exbibytes) of RAM. That’s several million Terabytes!

Memory (RAM) Limitation on x86 CPUs - 64 bit vs 32 bit

Now, that’s also 64-bit’s theoretical limit, which we have yet to actually reach by manufacturing it.

But 64-bit motherboards have allowed for dozens, sometimes hundreds of gigabytes and even (low single-digit) terabytes of RAM to be managed by a single system, whereas 32-bit motherboards and CPUs still have a hard cap at 4 GB of RAM utilization.

RAM Support on x86 CPUs and Motherboards

An x86-64 CPU is just a CPU that supports both 32-bit and 64-bit instruction sets.

This was done in the desktop space to maintain backwards compatibility with applications developed for or in 32-bit environments, which was the case for decades.

What Does 64-Bit mean? (Explained for Beginners)

If you see “64-Bit” on Software/Applications, it means the Software is able to use large amounts of RAM/Memory (>4GiB) and will most likely only run/be compatible with your PC if you also have a 64-Bit Operating System (e.g. Windows 10/11 64-Bit) and a 64-Bit CPU (99% of CPUs today are 64-Bit).

If you see “64-Bit” on an Operating System such as Windows 10 64-Bit or Windows 11 64-Bit, this means the Operating System is built to handle large amounts of RAM/Memory (>4GiB) and can run 64-Bit Software/Applications that then, in turn, can also use large amounts of RAM.

If you see “64-Bit” on a CPU/Processor (as in x86-64), this means the Processor/CPU is manufactured in a way that lets it handle large amounts of RAM and enables you to install a 64-Bit Operating System, which in turn lets you install and run 64-Bit Software.

Why You Should Always Use a 64-Bit OS, Even With 4GB or Less of RAM

So, if you don’t have more than 4 GB of RAM, should you bother with a 64-bit OS?

As long as your CPU supports 64-bit: yes, absolutely.

But what if you have less RAM than 4GB? Then there really isn’t a point in upgrading to a 64-bit OS, right?

Well, as long as your motherboard and CPU aren’t limiting you to 4 GB of RAM, you shouldn’t be settling for a 32-bit OS.

RAM may be expensive at times, but a RAM upgrade is still one of the cheaper hardware purchases that you can make for your PC.

Additionally, a modern 64-bit OS like Windows 10 is still made to be able to run with 2 GB of RAM.

While that obviously isn’t the ideal experience, you can maintain compatibility with the widest range of modern applications by using a 64-bit operating system today, even if you have 4 GB or less of physical RAM.

Another reason to opt for a 64-bit Operating System, is the option to actually run 64-Bit Applications – even if you have less than 4GB of RAM. Some Software only comes in a 64-Bit variant that won’t launch at all on a 32-Bit Windows installation.

Adobe’s Video Editing Software Premiere Pro, for example, is 64-Bit only and won’t run in a 32-Bit environment.

What To Do If Your System Doesn’t Support 64-Bit

Unfortunately, all I can really advise in this case is that it’s time for an upgrade.

A 32-bit CPU/PC can still be put to work or repurposed as something like a home media server or HTPC (Home Theater PC) pretty easily, though!

Even if it can’t support the latest software, a 32-bit PC is still perfectly capable if you’re willing to repurpose it.

To make full use of 64-Bit and large amounts of RAM, of course, you’ll need:

  • A 64Bit capable CPU (most modern CPUs are x86-64 today)
  • A 64-Bit capable Operating System (e.g. Windows 10 64-Bit, Windows 11 64-Bit)
  • 64-Bit Software
  • More than 4 GiB of RAM

FAQ

Will 128-Bit CPUs Ever Come Out?

From a commercial point of view, we don’t know. Although the hard limit on x64 (64-bit) CPUs seems astronomically high today, you have to remember that the 4 GB hard limit also enjoyed the same status when total system memory of a few hundred kilobytes was the norm.

We really don’t know how technology will take off (or won’t), so it’s difficult to answer this question.

That said, we aren’t anywhere close to hitting the limit for 64-bit processors and they’ll remain the norm for years to come, barring some unexpected changes in the computing industry.

SIMD (Single Instruction, Multiple Data) instruction sets like Intel’s AVX-512 can handle larger chunks of data in parallel, using even a 64-bit processor.

So, for now, there’s no need to expand into 128-bit processors other than when you begin to hit a 64-bit CPU’s max memory limit. 

What Makes a Computer Fast?

With an understanding of 32-bit vs 64-bit established, are you curious to learn more about how PC performance works?

Fortunately, you’re in the right place: I’ve already written a pretty extensive guide on what components make a computer fast, and how.

You can use the above link if you want the full guide, but here’s the hierarchy of what makes a computer feel “Fast”, in my opinion:

  1. Storage
  2. CPU
  3. RAM
  4. GPU
  5. Networking

For the majority of modern PCs, and a surprising number of older PCs, the main culprit behind a sluggish-feeling operating system isn’t the CPU or RAM.

Instead, it’s the slow HDD storage, especially the smaller 5400 RPM HDDs in low-power laptops, that are to blame for unreasonably sluggish computing experiences.

HDD vs SATA SSD vs PCIe 4.0 NVMe SSD

Slapping an SSD into a PC is a pretty much-guaranteed way to instantly improve its responsiveness and boot times a great deal, but it won’t suddenly make it better at handling RAM, CPU, or GPU bottlenecks, either.

I go into more detail on the “how” and “why” in the full guide, but if that tidbit interests you, check it out, especially if the order of my hierarchy seems off to you.

I’d love to hear your opinions or questions in the comments of that article.

What Does RAM Do?

So, what does RAM actually do in a PC, anyway?

Like always, there’s a full guide to break that question down in detail, but I can still give you a rough idea before I wrap up this article.

In fact, I feel inclined to, considering how much time I just spent talking about 32-bit operating systems and their RAM limitations.

Basically, the function of RAM in your PC is to be the workspace that your CPU uses to manage pretty much everything else.

If your CPU is an expert chef, your RAM serves as that chef’s cooking space.

As the scale and complexity of your workloads increase, it’s necessary for your RAM capacity to also increase in order to enable your CPU to maintain its peak performance.

Running out of physical RAM will force your OS and applications to fall back on a paging file, which is a pool of slower memory taken from your storage drives. This will be especially slow on an HDD but is somewhat mitigated with faster SSD drives, especially NVMe drives.

RAM vs Pagefile virtual memory usage

A 32-bit operating system is not only a hard limitation on RAM, it’s a hard limitation on the scale of projects and workloads that you can actually run on your PC.

There’s a reason why most modern applications are being built for 64-bit architectures and 32-bit apps are largely relegated to backward compatibility use cases.

If you’re curious as to how much RAM you actually need for your use case, consider Alex’s Full RAM Capacity Guide.

What are Motherboard VRMs and what makes them important?

On a final note of PC performance limitations, let’s talk about one of the least-covered ones: your motherboard’s VRMs.

Components of a VRM

Source: ASUS

VRMs are Voltage Regulator Modules, and they serve the important function of filtering all power that gets pumped into your motherboard before it makes its way to your processor. The better the VRMs, the cleaner and more stable the power delivery to your CPU is.

Why does this matter? In short, high-quality motherboard VRMs are what you need in order for your CPU to maintain its top performance at all times. This includes and especially applies to CPU overclocking.

If you’re interested in learning more about what VRMs are and how they work, head over to my Motherboard VRM Guide.

Over to You

And that’s it, at least for now!

I hope this article helped clear up what 64-bit means and what makes it so much better than 32-bit. While 32-bit devices still exist and some even have a place in the market with specialized applications, the 64-bit writing is on the wall and has been for quite a long time.

Meanwhile, the 128-bit writing is most likely to never be on the wall, or won’t be within our lifetimes, at least. Wild, right?

Leave a comment below and let me know what you thought of this article. Anything I missed? Any other questions about 64-bit hardware? Let me know! Also, consider heading to our Forum for other PC tech questions, or just to interact with the rest of our expert Community.

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Christopher Harper - post author

I have been a passionate devotee to technology since the age of 3, and to writing since before I even finished high school.

These passions have since combined into a living in my adulthood, and has made writing about myself very satisfying.

If you need any assistance, leave a comment below: it’s what I’m here for.

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