[Windows 8 General] SixSixSevenSeven:
Digitally signed drivers is a windows 8 feature NOT a 64 bit limitation.

For some reason you have 64 bit driver incompatibility listed as a good thing? Besides, that is also false. Some 32 bit drivers are indeed incompatible with 64 bit windows, but many do still work. From what I understand its something to do with kernel mode vs user mode drivers. In order for a driver to be receive a signature from microsoft it now requires either a dedicated 64 bit driver or at least 64 bit compatibility.

The difference between 64 bit and 32 bit systems goes much deeper than RAM, in fact the RAM difference is almost a side effect of the main difference. A 32 bit computer only has a 32 bit ALU and registers of max size 32 bits etc, it deals with everything as being 32 bits long, 64 bit is of course 64 bit. In binary you can represent a larger number in 64 bits than you can in 32 bits. In 32 bits you can represent a max value (unsigned) or 4294967295, include 0 as an option and there are 4294967296 values available, also how many memory addresses in RAM you can use, with each memory location being 1 byte you end up with 4294967296 bytes, or 4gb.

In 64 bits you can represent 18446744073709551616, which using the above RAM logic comes to ALOT, seriously, its more than a terabyte by the time I got bored of using my calculator. Windows doesnt support a terabyte no, but in theory it could, most motherboards are 64gb limited, or sometimes 32 (laptops often less).

64 bits however does not increase a computers memory efficiency in any way, only lets you use more of it. More RAM does not make your computer any faster if you were not running out before. Lets say you have 3 1 litre bottles and you need to store 2 litres of water, well having those 3 bottles wont be any better than having the 2 bottles you need to store the water present, the same happens in a computer, just with RAM instead of bottles and data instead of water.

That said there is a performance difference between 64 bit and 32 bit computers when doing maths on LARGE values. a 32 bit computer can only do maths on 32 bit numbers, if you need to do greater than 32 bit maths on a 32 bit machine you have to introduce alot of software steps first (most compilers or interpreters actually do this for you, its only if you insist on hand written assembly that you will have to manually add 2 64 bit numbers without the aid of the hardware so much), this is very very slow. A 64 bit computer can add 64 bit numbers natively. Generally when programming a 32 bit number is an int and a 64 bit number is a long, if you set your compiler to 32 bit and compile a program using longs then it will add the code for software addition for you, does mean that running a program compiled for 32 bit computers on 64 bit machines wont have access to the performance gains of said 64 bit machine. To use a long natively you would have to compile the program for 64 bit machines, in which case it will not work on 32 bit machines.

64 bit windows cannot handle more apps than 32 bit necessarily. You can actually hit the windows thread limit within a 32 bit system assuming each thread uses very little RAM. The thread limit is the same on both 32 bit and 64 bit windows. Now if you have a few proper programs and we arent talking a hypothetical situation of running thousands of programs using a few kb of RAM each then yes more RAM would help and if the amount of RAM required is greater than 4gb then of course 64 bit would be king - as would having a multicore computer.

Dedicated graphics cards DO count towards the 4gb RAM limit.

In a nutshell

32 bit program: no faster regardless of 32 bit or 64 bit.

64 bit program: faster than a 32 bit program running on a 64 bit machine (if it uses maths on very big numbers, or decimal points, they need alot of bits too). Will not run on a 32 bit machine.

32 bit drivers: will run on 32 bit machines. Will sometimes run (but not always) on 64 bit machines (same also applies to 64 bit software actually, 32 bit java often runs into issues on 64 bit windows, yet still if you hit the download button on the java website it downloads 32 bit by default, common cause of the OutOfMemory exception in minecraft is 32 bit java on 64 bit windows).

64 bit drivers: will only run on 64 bit machines.

drivers for both systems must be digitally signed for windows to install them, however there is actually a way to install unsigned drivers in windows 8. In order for a driver to receive a signature from microsoft then it must either a) work on both 32 bit and 64 bit machines or b) have 32 bit and 64 bit versions available seperately (older hardware may not have a 64 bit version available)

But yeah, you can't upgrade from 32 bit windows to 64 bit windows using the microsoft update tools. You need to totally uninstall windows, format your hard disk and install 64 bit windows from scratch as if you were installing windows on a new computer you had built yourself.

Someone gave me their old PC once, had 12gb of RAM fitted and 32 bit windows XP..... They didnt realise that they had purchased 12gb (they replaced the sticks that originally came in the PC) for a system that couldnt take 12gb....