32 bit vs 64 bit Comparison

[Lordbob75]

There are many, many threads on this one simple question: 32 bit or 64 bit Windows?
Well, there are a few things to consider when making this choice. The most obvious difference between 32 bit and 64 bit is the amount of RAM the system can use. The limit on 32 bit is 4Gb of RAM, whereas a 64 bit operating system (OS) can use up to 8Tb (128 in 64 bit Vista, and 192Gb in Seven).

HOWEVER, this is not the only difference, nor is it the only thing that should be considered. This post will cover the basics of 32 bit computing vs. 64 bit computing in an understandable and simple summary.
*If you are looking for a quick comparison, read the Basics and scroll down to the Pros and Cons and Conclusion sections*

The Basics
-The big difference between 32 bit systems and 64 bit systems is the “Addressable Space”. Each device in the system is assigned an address, which takes some of this space. Because the address space is limited, the more hardware you have, the more space is required to address them. Memory (RAM) will get what is left over, and it is this is what takes usable memory in a 32 bit system from 4Gb of RAM to around 3.25Gb.
-Most software today is written and optimized for 32 bit architecture. This means that there will not be a large performance increase by switching. However, for the few pure 64 bit programs out (such as 64 bit Photoshop), there can be a substantial difference.

32 bit OS
-A 32 bit OS can only address 4Gb of memory. Some of this is then allocated to hardware devices, usually dropping the available RAM to 3.25Gb or 3.5 Gb.
-The addressable space also applies to programs, giving a 2Gb limit of RAM to any one process. This means that 32 bit Photoshop can only ever access up to 2Gbs of RAM.
-Drivers are always a concern. Drivers for hardware usually have a 32 bit version, and there is usually not a problem with 32 bit drivers (finding or using).
-A 32 bit OS has a lower memory requirement to run. For Windows 7, the minimum RAM needed is 1Gb

64 bit OS
-A 64bit OS can address up too 8Tb of RAM (128 in 64 bit Vista, and 192Gb in Seven).
-The addressable space for a 64 bit process is 8Tb. However, a 32 bit process still has the 2Gb limit. So 64 bit Photoshop can access up to 8Tb of RAM, while 32 bit Photoshop (running on a 64 bit OS) will still only be able to access up to 2Gb.
-64 bit drivers used to be harder to find. However, since Vista 64bit drivers have become almost as common as 32bit drivers. In order for a driver to be WHQL-certified by Microsoft, there must be a 32bit and 64bit version of it, which has really helped in producing drivers. I have been running a 64bit OS since Vista and have yet to find a program that doesn't work or hardware that doesn't have a 64bit driver.
-64 bit OS needs more RAM to operate (minimum of 2Gb for Windows), and programs slightly more RAM. This is countered by being able to add WAY more RAM (I have never encountered a problem with 4Gb of RAM on my 64 bit system)
-There is no longer 16 bit compatibility

Misconceptions
-RAM limit is the only difference: This is obviously the most well-known difference, but is completely false. There are WAY more differences, some of which go way deep into computer architecture, and others that don't make a difference in performance.
-Non-compatibility: Some people believe that certain things will not work in 64 bit OS, etc. While 32 bit programs and 64 bit programs are NOT COMPATIBLE with the other system (64 bit and 32 bit respectively), Microsoft writes their Operating Systems with a Hybrid architecture (Windows In Windows, or WoW). This means that most 32 bit programs will work on 64 bit systems.
-No performance difference: This one is a quirky question. In general, there is not a large performance increase by switching to 64 bit. This is because most programs are still written with 32 bit architecture in mind, and do not need more than 2Gb of RAM. The difference starts to shine when running things like 64 bit Photoshop or CAD programs where LOTS of RAM is used.
-32 bit is better for gaming because of compatibility issues with the games or drivers: This one just isn't true. I have been running a 64 bit OS exclusively since Vista, and not once have I had a driver or game (except very old) incompatibility. If you are a gamer, a 64 bit OS would be the better choice, especially so you can use more RAM.

Pros (of switching to a 64 bit OS)
-Certain programs written for 64 bit computers can make better use of CPU and RAM, giving a LARGE performance boost (such as 64 bit Photoshop)
-More RAM is available
-64 bit is becoming more and more common. As average RAM in a system increases, there will be no choice BUT a 64 bit system.

Cons (of switching to a 64 bit OS)
-Certain programs may not be compatible with the new OS (very rare)
-Needs a minimum of 2Gb of RAM to run
-Needs a 64 bit processor to run (most made since 2003 are 64 bit)
-System uses more RAM to run the OS and programs
-Drivers may be harder to find and use

Conclusion
In the end, I usually recommend using a 64 bit operating system for all of its advantages. I have used a 64 bit OS for years now, and have encountered so few problems that I have no real reason to NOT recommend it.
However, if you plan on having less than 3Gb of RAM, have an older computer, or a 32 bit processor, I usually recommend a 32 bit system.

I hope this can help to settle all the threads about 32 bit vs. 64 bit operating systems.
Let me know if there is anything I can / should add.

Additional Information:
Windows 7 retail edition will come with 2 install DVDs, a x32 and x64. You can install EITHER version on your computer, but not BOTH. The retail key you received will work with both versions, but is only authorized for one install at a time.

~Lordbob

 

[joel406]

KUDOS to LordBob

Very well written.

Hope they sticky this.

 

[richc46]

Very good, rep deserved and given.

 

[Wishmaster]

Excellent summary.

 

[Lordbob75]

Thanks guys.

I saw that last post about 32 v 64 bit, and decided I was sick of people always asking (not their fault) so I asked Brink why there wasn't a post about it already.
He just told me I could write it, so I did.

Thanks for the rep and the appreciation!
I am just glad you all like it and it will help some people out.

~Lordbob

P.S. You guys gave me my 3rd turd

 

[kucing13]

good info Bob. Well done

 

[Lordbob75]

good info Bob. Well done

Thank you my friend.

~Lordbob

 

[NoN]

Good summary...!

But i'm afraid the title is a little confusing.

Should it would have been named " Comparison Test between x32 & x64 OS - EXPLANATION"

 

[Lordbob75]

Good summary...!

But i'm afraid the title is a little confusing.

Should it would have been named " Comparison Test between x32 & x64 OS - EXPLANATION"

I don't like my title now, I know. It's terrible. I am trying to think of a better one, but can't.

~Lordbob

 

[NoN]

Good summary...!

But i'm afraid the title is a little confusing.

Should it would have been named " Comparison Test between x32 & x64 OS - EXPLANATION"

I don't like my title now, I know. It's terrible. I am trying to think of a better one, but can't.

~Lordbob

PM the Admin...I'm sure he'll stick that thread and helps you modifying the title.

or something like:

"Comparison Test - Advantage from x64 To x32 OS - EXPLANATION"

"Pros & Cons From Win7 x32 to Win7 x64, OS - AN EXPLANATION"

 

[CarlTR6]

Very well done, Bob. I tried but could not rep you.

 

[joel406]

YA know... I kinda like the title.

Never change for nobody Lordbob.

We love ya just the way you are.

 

[Lordbob75]

PM the Admin...I'm sure he'll stick that thread and helps you modifying the title.

Shawn was the one who recommended that I write this, and I PMed him the link when I was done. He had logged out a few minutes before unfortunately, but he will see it when he comes back.

YA know... I kinda like the title.

Never change for nobody Lordbob.

We love ya just the way you are.

I don't intend to Joel. I felt that the title was very explanatory and worked, but didn't flow well.

What about:
32 bit vs 64 bit: A Simple Explanation
32 bit vs 64 bit: What Do I Choose?

~Lordbob

 

[NoN]

I did not meant hurting anyone...hope some tooks it gently

 

[kucing13]

32 bit vs 64 bit:What To Know?

I'm Just Kidding

 

[zzz2496]

Lordbob, nice explanation - but I think you misunderstood several items.

1. Memory bus: x86-64 is an ISA extension to the already legacy burdened x86. It has nothing to do with "Memory bus", memory bus works in hardware level, so on Intel Core 2 Quad series, it will run at max speed - on Intel i7/i5/i3, it will also run at max speed regardless OS's Kernel ISA compatibility.
2. The main differing case between 32bits and 64bits system are it's "Addressable space", this address space is what the processor use to address it's devices, be it a PCI/PCIe controller, a memory controller, a storage controller, a display controller, and many others. In 32bit Windows, you can address up to 4GB memory, but in practice you can only use 3GB - 3.25GB (depending on how many devices you have in your computer), why? Easy, because the address space is used by other devices, not only memory (memory is also a device, but critcally, memory is one of those devices that used a lot of addressing space...). Several x86 Intel XEON have PAE, with a modified kernel, it can address full 4GB along with other devices.
3. There are several types of Windows applications, I'll list some of them:
   • The "Classic" type: the type is compiled to a binary, and runs at full speed, depends critically to OS/Processor type.
     The reason why 32bit Windows apps can run mostly with minimum to no problem under Windows 64bit is because in Windows 64bit, there's a subsystem called "WoW", Windows in Windows. It's the one that's responsible to "virtualize" 64bit processor to a 32bit application. If you remember back in XP, XP has it's own "virtualization" subsystem for 16bit MSDOS programs, it's called "NTVDM.EXE". Both has it's own quirks, though. These applications, which compiled to 64bit native code, and if they link to a 32bit compiled library (some 32bit compiled .dll file), this application WILL FAIL. They need to link to a 64bit library too. Now comes the hard part, several native applications will call a method in 32bit library that has been deprecated in the 64bit version, thus crippling the said application. All this is a big messy headache inducing serious problem, thus MS comes up with "WoW" and "XP mode", and a HUGE push for developers to port their apps to either ".net" or compile it to x64 binaries.
   • The "Modern" type: this type is compiled to an intermediary data format, be it a .net CLR, or a JVM byte stream, and many others. It run mostly slower than compiled natively to a binary format, some are slower than others. It relies on virtual machine intermediary layer to execute. A .net app will need a .net framework to work, a Java program needs Java to work.
     This type of applications most of the time ignores the underlying hardware, because it doesn't even work natively. What you need to make sure that these program works in your computer is to have the correct VM for it to work, in .net case, you'd need the correct .net version, same as Java.
4. As for RAM, this brings another level of complicated factors. Our computers have it's RAM, those RAM are managed by the OS's Kernel. In a computer that has 4GB RAM, it doesn't mean that your application can use ALL of those 4GB by default. Here are the breakdown:
   • 32bit OS:
     • The limit of "User-mode virtual address space for each 32-bit process" is 2GB, which means you can only use 2GB max for each process in your 32bit OS, in plain english: Photoshop in 32bit Windows will only able to use 2GB max even if you have 4GB RAM. This type of kernel can't have 64bit binaries running in user space.
   • 64bit OS:
     • The limit of "User-mode virtual address space for each 32-bit process" is 2GB, which means you can only use 2GB max for each process in your 32bit OS, in plain english: Photoshop in 32bit Windows will only able to use 2GB max even if you have 4GB RAM. If the application is specifically compiled with "IMAGE_FILE_LARGE_ADDRESS_AWARE" flag set, it will be able to use 4GB max.
     • The limit of "User-mode virtual address space for each 64-bit process" is 8TB (default), or 2GB with "IMAGE_FILE_LARGE_ADDRESS_AWARE" flag cleared. In this case, Photoshop 64bit (with "IMAGE_FILE_LARGE_ADDRESS_AWARE" flag set) will be able to address 8TB of your RAM if needed.
   Reference: Memory Limits for Windows Releases - MSDN
   

Other than these issues, your post is GREAT
zzz2496

Edit: added reference.

 

[Lordbob75]

Lordbob, nice explanation - but I think you misunderstood several items.
[......]
Reference: Memory Limits for Windows Releases - MSDN
Other than these issues, your post is GREAT
zzz2496

Thanks for the added explanation (this will be incorporated into the first thread if you don't mind).
In some cases, it is more detailed than I wanted to go. This is because I wanted this to be a guide for people who didn't know a lot about computers to make a more educated decision on which type of OS to get.

I am not sure I entirely follow the memory bus explanation. Could you explain it a little more?

I know about the addressable space difference, however your explanation cleared a few things up for me, thank you. Now that I get it, I see how I can add it to the post to make it easier to understand for others.

The last part about the RAM is WAY more detailed than I intended to go (but again, thank you). Again, remember this is for your average user asking about 32 bit v 64 bit. However, I will add parts of this to the main post.

Thank you!

~Lordbob

 

[zzz2496]

Feel free to incorporate my post (or parts of it) in your original post

zzz2496

 

[iphone]

I dont think 64bit requires atleast 2GB ram as i ran 64bit Windows 7 on a laptop with 1GB :sarc:

 

[Lomai]

Thanks Lordbob