What Is The Difference Between 32-bit & 64-bit Windows?

641   What Is The Difference Between 32 bit & 64 bit Windows?People ask me on a daily basis, “What is the difference between a 32-bit and 64-bit Windows operating system?” Most of you are running Windows XP or Vista in its 32-bit iteration. But as hardware gets cheaper, people are curious as to what the 64-bit operating system has to offer. First let’s see if we can grasp the difference between 32- and 64-bit.

Think of your computer as a series of tubes that can either be 32 or 64 bits wide. When you have the smaller 32-bit size, there is more potential for bottlenecks to occur. Bottlenecks slow down your system because one process has to wait for another to finish before it can begin. But if you want to have 64-bit wide tubes, your computer needs to be thinking in 64-bit so your software and hardware all need to support 64-bit.


If you do not know the difference between 32-bit and 64-bit, I would have told you in the past that you are running a 32-bit version of Windows. But now with Windows 7 I am seeing more and more 64-bit operating systems shipped by default without the end users knowledge. Don’t get me wrong, a 64-bit system is better but you also need to be running 64-bit programs and have a 64-bit processor or else all the trouble of setting up the 64-bit operating system would be worthless.

On a 32-bit operating system, you are restricted to a maximum of 4 gigabytes of RAM. On a 64-bit operating system, you really do not have a limit. Let’s look at Wikipedia and find out the maximum amount of RAM for a 64-bit operating system:

264 addresses, equivalent to approximately 17.2 billion gigabytes, 16.3 million terabytes, or 16 exabytes of RAM.

That is a huge amount of RAM! Normally when you exhaust your physical RAM on a 32-bit system, it has to use virtual memory or hard disk space to pick up the slack. On a 64-bit system, you can install as much RAM as you can to cover your overhead. From here on, 32-bit operating systems will be referred to as x86 and 64 bit operating systems as x64. You can tell what you are running by right clicking on My Computer and choosing Properties.  Below is a shot of a 64-bit machine using 12GB of memory.

321   What Is The Difference Between 32 bit & 64 bit Windows?

And in this shot, we see a 32-bit machine trying to use 7GB of RAM.. Not going to happen!

322   What Is The Difference Between 32 bit & 64 bit Windows?

If you are running 3D modeling systems or AutoCAD systems, you can benefit from a x64 bit architecture but remember, you need to be running ALL x64 applications, print drivers and anything else you are setting up on your system to realize its full potential. Not all programs have been created for x64 yet and you will find yourself installing applications to your Program Files x86 directory. On a x64 machine, you will have two Program File directories — one for 32-bit and one for 64-bit applications.

So after reading through that and you still want to run a x64 operating system, you will need to make sure your processor supports x64. Most new servers and new computers bought this year or beyond will support x64 but you will still need to check. Here are some facts you should know (taken from ZDNet):

  • Almost all new servers sold within the last two years from AMD or Intel will have x64 capability.
  • Most mid- to high-end desktop processors from AMD or Intel within the last year have x64 capability.
  • Some higher-end Semprons have x64; lower-end Semprons do not.
  • No AMD Durons have x64.
  • All AMD Opteron processors have x64.
  • All AMD X2, FX, and Athlon64 chips have x64.
  • All Intel Pentium D and Celeron D chips have x64.
  • All AMD Turion notebook processors have x64.
  • All Intel Core 2 processors (mobile, desktop, and server) have x64.
  • No Intel Core Duo notebook processors have x64
  • No Intel Pentium M notebook processors have x64.

If you are still not sure if your processor can support x64 check out GRC’s SecurAble and let them help you figure it out! You might also want to check out Mahendra’s post How To Choose Between 32-bit & 64-bit Windows 7 Operating Systems.

If you are running a server that has all its hardware and software certified for x64, then you should install the 64-bit version but beware of device drivers and any 32-bit environments because if I used the word difficult, it would be an understatement!

The comments were closed because the article is more than 180 days old.

If you have any questions related to what's mentioned in the article or need help with any computer issue, ask it on MakeUseOf Answers—We and our community will be more than happy to help.

30 Comments -

0 votes

Greymarch

The article has a mistake. The article should really mention that 32-bit versions of Windows can only address 3 gigabytes of memory, not 4 gigabytes. Considering that most computer systems jump from 2 gigabytes to 4 gigabytes, that is an important distinction. A user who has 4 gigabytes, after reading this article, may think that they are using all 4 gigabytes with a Win32 OS, but they would be wrong. Please clarify this.

- Greymarch
I write about technology at my website
http://www.greymarch.com

0 votes

Dan Hutten

I was under the impression that 32bit can address 4gb of ram TOTAL, which includes video card and any other physical ram. if you have two 512 video cards in SLI, 32bit windows will only see 2.75gb ram. if you have one 256mb graphics card, windows will see 3.5gb

maybe i’m mistaken

0 votes

jollyrogue

Using the student offer here in the UK i was able to get hold of the 32bit Win7 Pro.

Anyone know if it’s possible to use the license key from that with a downloaded 64bit version? I’d like to buy more RAM for my laptop.

0 votes

Dan Hutten

good to know, thanks jon

0 votes

Greymarch

The article has a mistake. The article should really mention that 32-bit versions of Windows can only address 3 gigabytes of memory, not 4 gigabytes. Considering that most computer systems jump from 2 gigabytes to 4 gigabytes, that is an important distinction. A user who has 4 gigabytes, after reading this article, may think that they are using all 4 gigabytes with a Win32 OS, but they would be wrong. Please clarify this.

- Greymarch
I write about technology at my website
http://www.greymarch.com

0 votes

Sats

I toataly agree to greymarch.. RAM size should be 3 GB

0 votes

Dedo

I was under the impression that 32bit can address 4gb of ram TOTAL, which includes video card and any other physical ram. if you have two 512 video cards in SLI, 32bit windows will only see 2.75gb ram. if you have one 256mb graphics card, windows will see 3.5gb

maybe i’m mistaken

0 votes

Jon

Dedo is correct, although he has it slightly off. 32-bit OS can allocate 4 GB of physical memory, but it mirrors some of that memory with the memory some devices (like graphics cards) contain. Therefore, if you have 4GB RAM installed, and a 256MB VRAM video card, WinXP (32-bit) will mirror the 256MB of VRAM in it’s own RAM, and only allow 3.75GB of physical RAM to be allocated by the rest of the system. There are other devices on board that also contain their own memory, which the OS also mirrors, but graphics cards are the greatest impact.

0 votes

jollyr

Using the student offer here in the UK i was able to get hold of the 32bit Win7 Pro.

Anyone know if it’s possible to use the license key from that with a downloaded 64bit version? I’d like to buy more RAM for my laptop.

0 votes

Karl Gechlik

That will not work you will need to purchase a 64bit license.

0 votes

jollyr

damn.. ok, cheers Karl.

Maybe in the future i’ll purchase a 64bit version.

0 votes

Ben

A 32-bit program will work the same whether it’s installed on a 64-bit system or a 32-bit system.

0 votes

Karl Gechlik

That is correct.

0 votes

Doc

@Greymarch: Most 32-bit machines will have 3.5 or 3.75GB of usable address space, not 3.0 (depending on the video card’s graphics aperture (GART), which allows the OS to directly write to video memory). Having a 64-bit OS (on a 64-bit CPU) allows that memory to be “moved” above the 4GB mark, making it available again. Also, some Windows server OS’s allow more than 4GB of RAM in a 32-bit OS (but, notably, NO desktop OS’s) via Physical Address Extension (PAE), which Microsoft mysteriously doesn’t enable under 32-bit (but can).

I’ve also seen many machines ship with 64-bit Windows Vista, and know of one recent system that has Windows XP 64-bit Edition (which is built on the core of Server 2003).

You are also constrained to the memory your motherboard and OS can support – the system I’m typing on can only support 4GB, the XP 64 system can handle 8GB, and my Phenom quad-core can handle 16GB. The memory limits for Windows 7 are
Business, Pro, Ultimate: 128GB
Home Premium: 16GB
Home Basic: 8GB
Starter: 2GB

0 votes

Karl Gechlik

A 32 Bit OS CAN USE 4GB of memory that 4GB of memory can then be distributed to an on board graphic card that needs memory but if you are using an addon graphics card with its own memory than you can very well use and see 4gb of ram in Windows 32bit.

0 votes

Aeiluindae

Just to note, 4 GB of memory looks a awful lot like 3.7 GB, depending on how the OS is reporting it. For example, my Windows 7 system with 4 GB of RAM reports 4 GB, 3.75 usable on 64-bit windows, because of my integrated graphics, most likely.
Similarly (and this is why hard drives actual sizes are always smaller than the number on the box, a couple different reporting schemes (base 10 and base 2) are used. Base 10, as I understand it, uses a megabyte made of 1000 kilobytes, and thus reports more MB of space, where base 2, with a 1024 kilobyte megabyte, reports less MB. The box uses base 10, the computer uses base 2.

0 votes

Karl Gechlik

And i didn’t state that because it is confusing. But you are correct.

0 votes

Doc

@Karl Gechlik: No, no computer with a 32-bit OS can see the full 4GB. See the image at http://www.codinghorror.com/blog/2007/03/dude-wheres-my-4-gigabytes-of-ram.html

in order to see why (with only 4GB, take away the top gray bar): Your video card GART remapping (which is required for your CPU to write to video card RAM, whether your video card is in a slot OR onboard), DMA buffers, your motherboard BIOS, registers for controlling your other devices (USB, sound card, hard drive controllers, keyboard, mouse…almost anything you can see in Device Manager)…all of it detracts from the full 4GB of RAM you may have installed. Your memory is still there; it’s just that in order to function, your devices need memory addresses to talk to the OS, so they “cover” chunks of RAM with their own registers or memory.

0 votes

B.G.

Doc, your statement is incorrect. Your statement is solely based on the fact that Microsoft limit physical addressing to 4GB on 32-bit OS’s since after XP SP1. It is possible for 32-bit systems to use as much RAM as 64-bit systems.

Mr Gechlik, your calculation of 2^64 is incorrect as bit 63 is used as the NX bit, so halve what you have calculated.

0 votes

jollyrogue

damn.. ok, cheers Karl.

Maybe in the future i’ll purchase a 64bit version.

0 votes

Hitesh

@Karl Gechlik
I have one question?

why 32-bit called x86 rather than x32 ?
please can you find it?

Thanks for this artical..

0 votes

viraniac

Dear Hitesh,

the 32-bit is called x86 because the first 32 bit processor is 80386, after that there is 80486,80586….

so as you can see there is 86 common with all those processors. hence 32-bit is called x86

for more info see this link
http://en.wikipedia.org/wiki/X86

0 votes

Hitesh

Thanks viraniac,

Really What I Want To Know!

0 votes

Ray from Las Vegas

Ok, I have a 3gb w7/32 on Laptop, and 6gb w7/64 on dual core Desktop. On Desktop, I have never used 4g of memory. Even editing videos. (I don’t play games). I wish that the extra memory on x64 could be used for something.

What I see big time is that I need faster video card. Viewing HD videos takes way too much CPU.

0 votes

viraniac

Dear Hitesh,

the 32-bit is called x86 because the first 32 bit processor is 80386, after that there is 80486,80586….

so as you can see there is 86 common with all those processors. hence 32-bit is called x86

for more info see this link
http://en.wikipedia.org/wiki/X

0 votes

Oron

Win 64 is usually SLOWER than Win 32, because every instruction and every piece of data has to be loaded in a larger chunk, and access to RAM is a bottleneck. Win 64 will be faster only when large amounts of consecutive data need to be read, such as in heavy graphics applications, video editing etc. The main advantage of 64 bit over 32 is the ability to address as much memory as you have. Which system you should use therefore depends on your intended use, and I believe many users will be better off with Wind 32.

0 votes

Nick

I have supid question.
Is it any chance to install 32b XP instead of my 64b Win 7 on my laptop?

0 votes

mamohitsingh

good dvd

0 votes

Anonymous

Hi My name is Ramon i m a have question you can still run 64 bit processor amd under 32 bit operatin system? i m wondering because i installed 32 bit and i m having some trouble thanks

0 votes

Zalifah Ibrahim

Whatever it is, the article above is clearer than any of those i have read online. Thanks Karl.