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Analysis

Why bother with 64-bit Windows?

Posted on 7 Aug 2009 at 14:41

But applications that need to perform fast, high-precision operations typically don't rely on 32- or 64-bit processing at all. Instead they make use of extensions such as SSE4, which lets them work with registers that are actually 128-bits wide - even on a 32-bit processor.

The third difference between a 32-bit and a 64-bit operating system is the one that makes a significant difference in a real-world context. And it's the reason why, over the next few years, 64-bit processing is going to be important to more or less everyone.

Extra RAM: the big 64-bit advantage

In a few years you could well want to add more memory - and find yourself held back by limited address space

In a 32-bit system, the CPU can address 2 to the power of 32 different memory locations. That means a 32-bit OS can work with up to 4,294,967,296 bytes - 4GB - of RAM. If you install more it will simply be ignored. That 4GB maximum seemed impossibly distant when Microsoft introduced Windows NT 3.1, the first 32-bit version of the OS, back in 1993. Back then a typical desktop PC might ship with 4MB of RAM. Since then, though, the demands we make of a PC have grown enormously. We now expect our systems to be smooth and responsive, even when editing HD video or processing professional quality photographs. And so, as the graph on this page shows, our RAM demands have ballooned. If you buy a home PC today it will typically ship with 2GB of RAM or more, and it looks likely that 4GB will be the norm by next year.

We know from PC Pro reader surveys that it's common to install extra RAM in a PC over the course of its life. So even if a 32-bit OS is fine today, in a few years you could well want to add more memory - and find yourself held back by its limited address space.

The 32-bit memory limit is harsher than it may appear too: some addresses are reserved for system resources such as video memory, so you can't use a full 4GB of system RAM. We've found a 32-bit Windows Vista installation can typically recognise a maximum of around 3.4GB.

With a 64-bit address space such problems evaporate: a 64-bit OS can theoretically use up to 16 million terabytes of RAM. But don't expect to see everyday PCs equipped with thousands of gigabytes of memory in the near future. The 64-bit Professional, Enterprise and Ultimate editions of Windows 7 can use a maximum of 192GB of RAM, while 64-bit Home Premium is restricted to 16GB. And even these RAM allocations may require updated hardware: modern motherboards can often only use 8GB or 16GB of RAM, and we've yet to see one that accepts more than 24GB.

Further 64-bit benefits

A 64-bit operating system isn't necessarily any more robust than its 32-bit counterpart, but Microsoft has added extra technologies to 64-bit editions of Windows to improve security and stability. These include Kernel Patch Protection, which prevents third-party software from modifying key Windows files, and hardware-enforced Data Execution Prevention, which - if supported by the CPU - closes off potential vulnerabilities by making it impossible to execute code from an area of memory that's marked as data.

The most visible change, though, is that 64-bit editions of Windows automatically reject device drivers that don't have a trusted electronic signature. That makes it harder for your system to be brought down by an untested driver - or by a virus masquerading as one - although it also makes it harder to tweak hardware drivers yourself should you wish to do so.

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User comments

64 bit

I agree that it makes good sense that if one is going to be installing Windows 7 as a clean install then opting for 64 bit is the sensible choice. I have a couple of observations from having used 64 bit Vista for a couple of years:
Firstly memory; although Vista recognises the 8 GB of RAM that I have, the sidebar gaget that monitors memory use shows only 2 GB in use pretty much all the time.
Secondly, one of my biggest frustrations has been with Adobe Reader, which, even after all this time, still does not work with 64 bit Vista properly, in that the thumbnails and previews in explorer and Outlook do not work. I have 32 bit Vista at work and Reader works fine on that. I really hope Adobe can get its act together for Reader 10, perhaps to work properly on Win 7.

By perriss on 12 Aug 2009

Adobe Reader

Get rid of this resource hungry app and use foxit reader it takes up less memory does exactly the same job and is also free to download

By littleb on 13 Aug 2009

64-bit Drivers

I’ve been keen to switch to 64-bit, and I’ve had mixed experiences.
Testing Windows 7 Beta 64, I found the system very responsive (using 4GB RAM), but there are still too many unsupported devices/software for me to warrant moving to 64-bit –the issue, driver support!

For example I occasionally use music production software –the version I have won’t work on 64bit, and there are no 64 bit drivers for the MIDI/interface I use. I found a relatively small amount of applications and hardware ran into this problem, but it was still considerable enough for me to stay 32bit.

I’m now using Windows 7 RC 32, with (so far) no compatibility problems. Once manufacturers fully support 64bit, the time will be ripe to move.

By alexg400 on 18 Aug 2009

On page 3 under "Extra RAM: the big 64-bit advantage"
it should read "2 to the power of 32 addresses (or 2^32 addresses" not 232 addresses.

By jbarnett on 19 Aug 2009

windows 7 (7600)

Now that the retail version is out, there is no reason not to install it.

By jonhoneybull on 20 Aug 2009

Jump on the bandwagon now or later

Duh, later. It'll be even cheaper. Unless 3.4GB is actually not enough for what you're doing right now then there's not a whole lot to force you to upgrade.

If you're performing the sort of high precision math that 64bit helps you'll know you are.

By steviesteveo on 24 Aug 2009

Correction

Good spot jbarnett - error in transcription. Now corrected. Thanks.

Barry Collins
Online Editor

By Barry_Collins on 24 Aug 2009

The article is misleading

The 32-bit limit on memory addressing is just that, a limit on the maximum the system can address in one go. You are able to buy 32bit windows server operating systems that can make use of more than 4GB of RAM for this reason. The total available memory limitation is due to the coding in windows. Maybe the article should reflect this.

By storm311 on 1 Sep 2009

The article is misleading

The 32-bit limit on memory addressing is just that, a limit on the maximum the system can address in one go. You are able to buy 32bit windows server operating systems that can make use of more than 4GB of RAM for this reason. The total available memory limitation is due to the coding in windows. Maybe the article should reflect this.

By storm311 on 1 Sep 2009

Double precision

There is no need to use a 64 bit OS or application to take advantage of double precision floating point. x86-64 CPUs support double and extended precision in both 32 and 64 bit mode.

Something that isn't mentioned is that like-for-like performance can actually decrease in some situations because of the larger cache footprint of 64 bit code.

By markh on 11 Sep 2009

get your facts right

Firstly, NO 32bit operating system can utilise 4GB RAM, including Win7 32bit and 2008 Server R2!

Secondly, many programs perform about 20% faster using 64bit.

Thirdly, the number of programs that REQUIRE 64bit processing is rising.

Fourthly, the amount of RAM required to run Office 2007 is over 1GB and will rise with Office 2010, ditto for IE and most other applications. Win7 might use the same amount of RAM as Vista now, but after a couple of service packs it will probably use more, as was the case with every other operating system Microsoft produced. Why inflict a 3.2GB RAM limit on yourself?

By skgiven on 24 Sep 2009

@skgiven: Yes, it is possible to utilise >3ish GB RAM on a 32 bit system, using techniques such as PAE. However, MS decided not to implement them on Vista (for backwards compatability reasons?), but I'm pretty sure some server OS's can address more than 3 GB despite being 32 bit.

By qwertyqwerty87 on 24 Sep 2009

No guarantee it will work...

I have a decent motherboard that supports up to 8Gb RAM, and Vista 64, but when I upgraded from 2Gb to 4Gb RAM it will no longer boot. I also have a 32bit XP partition and ironically, that boots fine with 4Gb (although it only recognises 3.5Gb as expected). It seems I am not the only one with this issue, but there is no known Vista fix as yet. I am currently therefore using my PC with 3Gb, and with a brand new 1Gb stick of RAM helpfully sitting on the desk.

That said, I have had no other problems with the 64 bit version of Vista, so I would still opt for this over the 32bit version. In my case, I have kept my 32bit XP partition for only 2 reasons - my old scanner only has 32bit drivers and Crysis runs much better in XP.

By simonjm3 on 3 Oct 2009

There is no matter for debates

Who still can use 32 bit - let him use it. It's true, that 32 bit systems still have more support with drivers and applications. It is VERY annoying, when you MUST move to 64 bit and have to say goodbye to such applications as VPN client SecuRemote of CheckPoint. It is rediculouse, that some Software makers do not care that sometime we can not more use 32.
The key /3GB is very limited in capability. Sometimes you can not fit simultaneously into limited address space both windows kernel and application job even with tricks of /userva=????.
I have several examlpes of CAD files from Parasolid and NX that even can not be opened by NX Unigraphics with the Error "Out of memory" in spite you still have plenty of unused RAM+Virtual. 64 bit let them be opened by the same application without any problems.
I reinstalled many of former 32 to 64 from scratch. System can not come usually if you use incompatible DIMM modules or BIOS is not upgraded (it was the issue of excellent Intel D955XBK motherboards that all series came with the old BIOS)

By Gennadii on 1 Nov 2009

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