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[cleggy]

I am currently running a Dell quad core desk top on Windows 7 Ultimate 32 bit version, is it worth upgrading to 64 bit version ?

The machine is fast enough and with enough RAM I just wonder if the gains out weigh the hassle of reinstalling everything after the upgrade.

[zirk]

Sometimes believe if its running smoothly, 'dont try a fix something that isnt broken' when it comes to computers. 

[cleggy]

I am quickly coming to the same conclusion.
I don't really need to address more than 4 gig, don't do gaming, don't use multi programs simultaneously and the machine is fast enough.

Seems to be too mush hassle having to be a clean install

[Kevin Wood]

Sounds like you don't need 64 bit.

It's really only necessary if you need to address significantly more than 4G of memory, since windows won't use PAE in 32 bit mode.

You also have to remember that 64 bit software is generally not as efficient in using memory as 32 bit software, so you are much better off sticking to 32 bit until you actually need to move to 8G+ of RAM.

[Shackeng]

Sounds like you don't need 64 bit.

It's really only necessary if you need to address significantly more than 4G of memory, since windows won't use PAE in 32 bit mode.

You also have to remember that 64 bit software is generally not as efficient in using memory as 32 bit software, so you are much better off sticking to 32 bit until you actually need to move to 8G+ of RAM.

What's PAE Kevin?

[Stemo]

Our PC came with 64 bit pre-installed, but has only got 4 GB of RAM.

[Marks DTM Calib]

Sounds like you don't need 64 bit.

It's really only necessary if you need to address significantly more than 4G of memory, since windows won't use PAE in 32 bit mode.

You also have to remember that 64 bit software is generally not as efficient in using memory as 32 bit software, so you are much better off sticking to 32 bit until you actually need to move to 8G+ of RAM.

What's PAE Kevin?

Physical Address Extension

Is a technique which allows a 32 bit system to address memory sapce above the 4Gb limit

[Kevin Wood]

Sounds like you don't need 64 bit.

It's really only necessary if you need to address significantly more than 4G of memory, since windows won't use PAE in 32 bit mode.

You also have to remember that 64 bit software is generally not as efficient in using memory as 32 bit software, so you are much better off sticking to 32 bit until you actually need to move to 8G+ of RAM.

What's PAE Kevin?

Physical Address Extension - a means by which a 32 bit operating system running on a PC can address memory over and above the 4GB limit. If the operating system supports this, you can utilise up to 64GB of total RAM, but each process can only utilise up to a 4GB address space. It's a kind of halfway house to 64 bit.

[TheBoy]

I'd recommend 32bit if 4Gb fitted (only approx. 3Gb will be useable), and 64bit if more than 4Gb. 64bit data structures need more RAM than their 32 bit counterparts.

[Shackeng]

Sounds like you don't need 64 bit.

It's really only necessary if you need to address significantly more than 4G of memory, since windows won't use PAE in 32 bit mode.

You also have to remember that 64 bit software is generally not as efficient in using memory as 32 bit software, so you are much better off sticking to 32 bit until you actually need to move to 8G+ of RAM.

What's PAE Kevin?

Physical Address Extension

Is a technique which allows a 32 bit system to address memory sapce above the 4Gb limit

Thanks.....I think?

[Marks DTM Calib]

With a 32 bit system you can only physicaly address 4GB of memory space.

When you consider that there are various devices other than memory also requiring a spot on the memory map, you find that your limit on usable physical memory is circa 3GB.

So if you have or need more than 3GB of memory then you need 64bit windows idealy.

There is a get around, and that is PAE which is a technique to allow a 32 bit setup to address beyond the 4GB limit (but its a work around rather than an ideal)

[TheBoy]

So if you have or need more than 3GB of memory then you need 64bit windows idealy.

There is a get around, and that is PAE which is a technique to allow a 32 bit setup to address beyond the 4GB limit (but its a work around rather than an ideal)

Can I add my 2p to that?

Due to larger data structures with 64bit, it only really pays off (if you need all the memory) beyond 4Gb.  Most 32 bit systems are in the region of 3.2-3.5Gb useable (except my works lappy, just checked, 2.9Gb useable, that's the lowest I've ever seen ).  If you don't run out of RAM, there are no real performance benefits to either. 32bit drivers used to be more mature, making the jump to 64bit more of an ordeal, but that's mostly resolved, as to get on MS's HCL you have to provide 32 and 64bit drivers, since Vista.

Most consumer PCs are 64bit now, purely for marketing reasons - bigger must be better.


PAE is a workaround, and generally only implemented on server and workstation class machines, but did work very well for years, until 64bit Windows/Linux became the norm. That said, back then we were talking of servers with a quintet of 32bit single core CPUs and 16Gb RAM being the mutts nuts. Today, 4 64bit CPUs with 12 or 16 cores, paired up with 512Gb RAM per blade is not uncommon, and a pair of multicore CPUs and 256Gb blades are the norm.

[Kevin Wood]

It would be interesting to figure out at what level of RAM a 64 bit machine achieves parity with a 32 bit machine on memory usage. I think I'd agree that it's not worthwhile on a 4GB machine. They are probably only shipped with 64 bit Windows to stop punters taking them back, moaning that it only reports 3.x GB ram.

[Marks DTM Calib]

Most 32 bit systems are in the region of 3.2-3.5Gb useable (except my works lappy, just checked, 2.9Gb useable, that's the lowest I've ever seen ). 

Thats very dependent on the designer, the chipset, peripheral chips used etc as its down to the address lines available and the address space required.

Some moons ago when I was designing processor systems (mainly power PC stuff), we used to produce the memory maps and for some parts, it was easier to allocate say 50% of the addressable space to memory (address bit 31 being effectively the chip select for SDRAM) on systems with circa 1G of memory, then dot the other key items such as ASIC's, FPGA's, MAC's, DSP's etc etc at set spacing (makes address decode much easier).

The modern processors have memory management sections in them where you can do this (rather than external CPLD's which we used) but there are still rules associated with them which can limit things significantly.

[TheBoy]

Most 32 bit systems are in the region of 3.2-3.5Gb useable (except my works lappy, just checked, 2.9Gb useable, that's the lowest I've ever seen ). 

Thats very dependent on the designer, the chipset, peripheral chips used etc as its down to the address lines available and the address space required.

Some moons ago when I was designing processor systems (mainly power PC stuff), we used to produce the memory maps and for some parts, it was easier to allocate say 50% of the addressable space to memory (address bit 31 being effectively the chip select for SDRAM) on systems with circa 1G of memory, then dot the other key items such as ASIC's, FPGA's, MAC's, DSP's etc etc at set spacing (makes address decode much easier).

The modern processors have memory management sections in them where you can do this (rather than external CPLD's which we used) but there are still rules associated with them which can limit things significantly.

Absolutely, which is why all systems are different. The majority of consumer oriented PCs will give 3.2-3.5Gb, very rarely more. Often the biggest culprit is the GPU taking a fair chunk (eg, 256Mb). Virtually all PCI/PCIe devices, including onboard ones, will demand a chunk, although these tend to be quite modest ranges. Obviously, industrial control cards can eat in to this hard, depending on the design of them. As you say, if you address it on the top address bit only, that's 2Gb lost straight away

The lowest I've ever seen on a normal PC is my works lappy, giving just 2.9Gb.