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Windows 7: Should I Install 64-bit or 32-bit Version? (x64 vs x86)

I have heard that if a laptop has more than 2 GBs of RAM (my laptop has 3 GBs of RAM), then one must use a 64-bit OS for better performance. So how the OS effect the performance of laptop and if what I have heard is true?

From my personal experience, I have seen that 32-bit OSes degrade the performance of my laptop as compared to the respective 64-bit OS; one parameter is that it consumes more battery.

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That number should be 4 Gigs of RAM. The 32 bit mode can only address 4 Gigs. – Keith Aug 12 '11 at 9:43
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@Keith: Once you take into account graphics card memory and so on, 3.3GBs is generally the max usable RAM point. Also, 32-bit Windows has the limitation of 2GB per app and 2GB for the OS, so 3.3GBs can't be all dedicated to one process. – William Lawn Stewart Aug 12 '11 at 10:14
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@William, yes that's how the OS allocates it. But speaking of the actual hardware, the 32 bit mode can't address more than 4 Gig without PAE. With PAE you can get more, but that's much slower than just switching to long mode (64 bit) and using a 64 bit OS. – Keith Aug 12 '11 at 10:25
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closed as exact duplicate by Nifle, Sathya♦ Aug 12 '11 at 11:32

This question covers exactly the same ground as earlier questions on this topic; its answers may be merged with another identical question. See the FAQ for guidance on how to improve it.

5 Answers

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In 32-bit Windows, due to how Windows manages memory, applications can't use more than 2GB each (including paging file space).

Because of this, even if you have under 3GB of memory 64-bit still provides an advantage.

64-bit also allows for the use of the 64-bit CPU registers and 64-bit CPU instructions, which might increase performance.

The only situation where 32-bit is better is when you're so strapped for memory that the size difference of pointers matters, and if that is an issue, then you should probably be buying more memory, because the system would be slow regardless of what OS it would be running.

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Not completely sure, but I think 32Bit CPUs already offer 64Bit registers (MMX, SSE etc). This is besides the point you made, just as an annotation. – StampedeXV Aug 12 '11 at 9:41
@Stampede: Just checked, x64 offers an extra 8 general purpose registers and 8 SSE registers. Good point on x86 offering 64bit registers, missed that somehow =) – William Lawn Stewart Aug 12 '11 at 10:12
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up vote 4 down vote

A 32bit OS can use about 3GB of RAM, while a 64bit OS can use a lot more. (theoretically 2^64 bit).

So for your Laptop there is no real need to use a 64bit OS. If you'd like to update your RAM to 4, 8 or even 16 GB you need a 64bit OS to really use the RAM.

So it will increase performance through the possibility that it can use more RAM.

I don't think there is a reason for the same OS in 32bit and 64bit to consume different amounts of power (at least not measureable). Also performance is usually equal (besides what I said about RAM usage).

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It is correct, but there is a little note. 32bit processors are capable of PAE feature. It means that they can address a more than 4GB memory. But you need special version of OS kernel to enable this feature. This means that you may be faced with issues (driver instability and so on). Also OS won't give to each user program more than 2-3GB memory. 64bit systems don't lack it. – George Gaál Aug 12 '11 at 11:43
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up vote 1 down vote

If the processor can support a 64-bit OS, and you don't need to run any applications that are incompatible with a 64-bit OS, then 64-bit is usually preferred because the system will often yield better overall performance.

Now for you, there is one additional criteria that you mentioned -- battery charge consumption. How much of a difference have you noticed? Is it only a few minutes or something far more significant such as more than 20? If it is significant, then this is definitely an additional factor worthy of consideration.

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up vote 0 down vote

The 32-/64-bitness should not affect general performance much. I'd just the 64-bit version just because it's more future-proof.

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up vote 0 down vote

Actually, a 32 bit operating system can use up to 3.89g of RAM. Windows XP has an internal issue, which can not allocate more than 1.95g of RAM to a single process.

If your using a laptop with only 2g of RAM, you will be better off using windows xp 32-bit, unless your looking to upgrade you memory to 4g or more.

Trying to run Windows 7 64bit on your laptop might be a little heavy for just 2g of RAM.

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where did you get the 3.89g from? – StampedeXV Aug 12 '11 at 10:57
32bit OS with 4GB usually shows 3.2 - 3.9GB available physical memory. Remaining memory is consumed by hardware things like BIOS, memory-mapped registers and so on. – George Gaál Aug 12 '11 at 11:38
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