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Whats the actual differance with 64 bit and 32

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a b à CPUs
July 8, 2009 5:42:43 PM

OK so i have been going around in circles on the net and just really want to know what the actual technical (please get as techy as you need to to explain properly) difference is when running a 32 bit OS compared to a 64 bit OS.

I'm assuming that there must be parts of the CPU that are dormant when running 32 bit ? so would this mean it uses more power in 64 bit mode. If so does is it enough for more volts when running an OC ?
How does it affect things as far as the bandwidth goes ? again assuming the app is codded for 64 bit then its processing the data twice as fast, or is it just twice as much ? so what effect does this have if any on the buses ?

A link to a good article would be appreciated. lastly is computing at a point now where 64 bit is giving us more than the use of extra Ram, whats the support like now. I know its better than ever and im actually running the 64 bit W7RC but havent had it long enough to run enough tests yet.

Thanks in advance for any help/replies

Mactronix
July 8, 2009 6:00:42 PM

the actually difference is actually very simple, implications there of not so much. In a computer instructions are issued to various components, similar to people talking. The difference is people can use different length words: the, has=3 letters; have=4 letters... In a computes every thing is the same length in a 32bit os all the words are 32bits long, and a 64bit computer has 64bit long instructions.

The reason you can have more ram is the instructions got longer example: 99 or 999. If you were only allowed to use two characters the highest number you could count to is 99 were as if you can use 3 characters you can now count to 999.
FYI: there is a work around for this but that is another discussion.

Nothing is dormant it is just used differently, not more work not less work just working differently.
July 8, 2009 6:03:57 PM

Good Question....... good answer [:rocket_sauce:1]
Related resources
a b à CPUs
July 8, 2009 6:16:11 PM

505090 said:
the actually difference is actually very simple, implications there of not so much. In a computer instructions are issued to various components, similar to people talking. The difference is people can use different length words: the, has=3 letters; have=4 letters... In a computes every thing is the same length in a 32bit os all the words are 32bits long, and a 64bit computer has 64bit long instructions.

The reason you can have more ram is the instructions got longer example: 99 or 999. If you were only allowed to use two characters the highest number you could count to is 99 were as if you can use 3 characters you can now count to 999.
FYI: there is a work around for this but that is another discussion.

Nothing is dormant it is just used differently, not more work not less work just working differently.

Best explanation in laymen's terms that I've seen in a while, I'm not going to pretend that I know whether it's correct or not but it's better than this one.
July 8, 2009 6:23:39 PM

^ agreed
a b à CPUs
July 8, 2009 6:58:00 PM

Thanks for the explanation 505090.
So its like you can run instruction like do this and this in 64 bit. but do this and then that in 32bit.
More efficient and then obviously gives a speed boost because more can be done in one pass so to speak.
Dont know if i fully understand it now but i think i have a lot better handle on it than i did.

Thanks
Mactronix
a b à CPUs
July 8, 2009 7:03:13 PM

Bits and the binary numeral system goes hand in hand. The number of bits a CPU has represents the size in "binary digits" that the CPU registers/buses can handle. The two major impacts are arithmetic precision and memory addressing.

With 32 bits, the CPU sometime had to do calculation in two passes for very large numbers (>32 bits), but now it takes only a single pass. Moreover (not sure tho), floating point calculation in 2 passes can be less reliable than single pass. For most users this doesn't have that big of an impact as 64 bits calculation is mostly used in scientific or engineering domains.

For addressing, it means the CPU can now use up to 2^64 bytes of memory instead of 2^32.
July 8, 2009 7:19:45 PM

The 64 bit CPU's now from AMD and INTEL are basically modified 32 bit cpu's. They have extra general purpose registers that can be used for pointing to memory locations or other things. The biggest benefit on the desktop is the use of more than 4 gigs of ram directly by the processor (no tricks like PAE). In order to understand the real differencees, you need to know about programming, because you need to know what registers are and how they are used in the cpu's.

http://en.wikipedia.org/wiki/AMD64#AMD64

I don't know all of this either and this looks good, so I am gonna read it too !
July 8, 2009 7:55:11 PM

The very basic principle of 64 vs 32 is the addreesing of memory and proceessing of integers.

The 64Bit: It can handle integers up to 2^64
The 32Bit: It can handle integers up to 2^32

That is not 2 times as much. It is actually about 4 billion times bigger. But not many apps use ingeters and and addresses bigger than 32bits long so the performance increase is not that big (even 64bit apps might never reach 64bits)

This also explains the 4gigabyte limitation of 32bit OS's

2^32 is equal to 4 294 967 296 bytes
4 294 967 296 / 1024 = 4 194 304 kilobytes
4 194 304 / 1024 = 4096 megabytes
4096 / 4 = 4Gigabytes


2^64 is equal to 4GB squared x 1024^3
Thats too much for my maths but it is more that 17 billion gigabytes
July 8, 2009 7:58:29 PM

well then
a b à CPUs
July 8, 2009 9:02:06 PM
July 8, 2009 9:34:31 PM

Theres a few negatives of using 64bit as well. If the instruction set runs under 32 bit alot, the 32bit could actually be much faster. To code to 64bit when its not needed can be a waste.
July 8, 2009 9:47:11 PM

mactronix said:
Thanks for the explanation 505090.
So its like you can run instruction like do this and this in 64 bit. but do this and then that in 32bit.
More efficient and then obviously gives a speed boost because more can be done in one pass so to speak.
Dont know if i fully understand it now but i think i have a lot better handle on it than i did.

Thanks
Mactronix



yes and no, the instructions are longer but you have to remember we are talking about bit's here. (a bit is either a 1 or 0) So far i have not seen any benchmark that shows a significant performance difference between 32 and 64 bit.
a b à CPUs
July 8, 2009 9:56:21 PM

JAYDEEJOHN said:
Theres a few negatives of using 64bit as well. If the instruction set runs under 32 bit alot, the 32bit could actually be much faster. To code to 64bit when its not needed can be a waste.



If by "alot", you mean "If the instruction set is better optimized for 32 bit...", then I could buy that. But IMHO, it's a matter of programmers writing proper code, rather than anything inherent in the instruction set. Hell - Look at Creative!! I mean, was anyone *really* expecting an improvement just because they dumped their sh*tty drivers into a 64 bit compiler... :lol: 
July 8, 2009 10:07:46 PM

LOL too true. Its more a BW thing anyways, where perf wouldnt be that different, but itll eat up more ram doing the same thing, carrying all those longer instructions doing the same thing
July 8, 2009 10:08:44 PM

silly guys with there tech talk..

its 32 duh..
a b à CPUs
July 9, 2009 8:52:26 AM

Well i did more or less ask people to get techy, im not an IT Major or anything but i can get my head around most of it.
Thanks for the articles Scotteq, i will work my way through them.
@ 505090,
I'm beginning to see what you are saying about the benchmarks, i have ran a few games now with Fraps and to be honest some are loosing FPS, only 1 or 2 but i have yet to find a game that actually gains by running 64 bit. All the cut scenes seem to run noticeably faster but then i guess that could be just down to having extra Ram available and not to do with 32vs 64 at all.

Now here's the crunch question (again) :whistle:  ,

32 bit W7 seems that bit snappier around the desktop, boot time is faster and for any given application its a possibility that it could not be supported under 64 bit.
I have already seen a healthy jump in performance with W7, the MT aspect of DX11 is said to give benefits regarding FPS, even on a non DX11 card. So is it just bottom line that if i do decide to go 64 bit that i can run more than 3. whatever GB of Ram ?
I could see that it may help if you had a native 64bit application and did lots of trans coding/Video work etc.
Also just thought, does the amount of Cache on the CPU make any difference to the CPU's ability to run 64 bit, or is it not really relevant.

Thanks for all the input guys, i really appreciate it.

Mactronix



a b à CPUs
July 9, 2009 9:31:31 AM

From memory, current CPUs only use a 48-bit memory address range, not 64-bit. It's not really a problem though, since even servers can't use up that much memory (yet).
July 9, 2009 12:01:45 PM

Mactronix,

Remember the games you are running are probably 32 bit games, so there will be very little performance difference between running them under a 64 or 32 bit OS. As you point out you might even find worse performance on a 64 bit OS. Each component needs to be addressed in isolation. It would be nice for the development companies to release 32 and 64 bit complied versions of all their programs - no one actually develops in machine code any more - everything is compiled (or interpreted) these days.

Generally - if you have a native 64 bit CPU you should try to run 64 bit compiled code. Just for the majority of programs (including some drivers) you won't find this available and, unless you go open source, nor will you be able to compile the code yourself.
a b à CPUs
July 9, 2009 12:15:59 PM

Hmm,
Lots of good info and advice to think about there guys, Thanks
Just finished with the links Scotteq posted and it seems as if its rock and a hard space time.
Games have started to get to a point where its reasonable to expect them to start encountering the 2gb limit, but implementation of 64 bit applications (like Mozilla Thunderbird for example which doesn't support 64 bit at this time) while a hell of a lot better than it was, isn't what it could be.
Still you never get anywhere by playing it safe all the time do you, sure i may get issues with the odd app not running or get driver issues with some things, certainly staying 32 bit would give me an easier ride for a while.
Then again more and more stuff is getting 64bit support and if i do get any major headaches from it i know a few people who can point me in the right direction again ;) 

Thanks a lot again guys, W7 64 here i come :D 

Mactronix
a b à CPUs
July 9, 2009 1:09:59 PM

Mac - For insurance and/or peace of mind you can set up a dual boot... It'll make you feel better TWICE!!



The first time you'll feel better because you're applying your technical knowledge to ensure you'll have the proper tools at hand to be able to do whatever you want.


The second time you'll feel better is when you're wiping the 32 bit OS's partition and recovering all the hard drive space that you used the first time you made yourself feel better!!! :D 


No Fail Solution! :D 
a b à CPUs
July 9, 2009 1:10:52 PM

I think most of us look at the 64 bits subject the wrong way. I think we should rather see 32 bits as a potential bottleneck instead. Like RAM, adding more when you had enough won't change a thing.

For computers using only 32 bits numbers and not needing the 64 bits addressing, there will be no benefit. For scientific, engineering and RAM needing contexts, then great. But one example that might affect most of us is encrytion, I don't have numbers, but I wouldn't be surprised that applications using 128 bits encryption keys would benefit from 64 bits CPU as it would require much less "loads" to process the whole thing (that is if the algorithm was optimized for 64 bits of course).
a b à CPUs
July 9, 2009 1:39:39 PM

To be honest, For insurance and/or peace of mind im going to keep the XP drive, the wife went all funny when she turned on the PC and didnt find XP staring at her. Never mind that i had transfered all her settings etc across so all the hot keys still linked to Web and E-mail ie no differance. The way she reacted you would have thought i took the keyboard away and gave her a set of levers that controlled a bag of worms or something :lol: .
Anyway i have XP on a 500gb disc and both W7 32 and 64 on a differant disc at the minuite. Guess i will add a new 500-1 TB drive for the W7 64 when it comes out.

Mactronix
a b à CPUs
July 9, 2009 3:16:35 PM

Zenthar said:
I think most of us look at the 64 bits subject the wrong way. I think we should rather see 32 bits as a potential bottleneck instead. Like RAM, adding more when you had enough won't change a thing.

For computers using only 32 bits numbers and not needing the 64 bits addressing, there will be no benefit. For scientific, engineering and RAM needing contexts, then great. But one example that might affect most of us is encrytion, I don't have numbers, but I wouldn't be surprised that applications using 128 bits encryption keys would benefit from 64 bits CPU as it would require much less "loads" to process the whole thing (that is if the algorithm was optimized for 64 bits of course).



On a philosophical level, I agree - As long as the OS has "enough" to support your choice of hardware and programs, then

As a practical matter, it's a bit of a different story though... Even forgetting RAM limitations: Games have already been capable of surpassing the 2GB worth of application space available in 32 bit windows for a couple years now. And with GPU memory growing as much as it has, the address space needed to cover system needs and MM I/O in 32 bits is a rather precious commodity.

With a 64 bit OS, your hardware once again dictates what can and can't be done because for practical purposes it's not possible to run out of address space on the desktop.







mactronix said:
The way she reacted you would have thought i took the keyboard away and gave her a set of levers that controlled a bag of worms or something :lol: .



Shhhh... That's the new UI for Windows 8... :lol:  Now, excuse me while I extend that thought into "Touchscreen" jokes... :na: 



More seriously - Do the dual boot thing... Then maybe later you can offer to create your wife a user account (only takes a few clicks). Sit her down, and ask her what she wants it to be like. Pin her favorite apps to the taskbar for her. Show her how to use the (much superior to XP, IMO) search to find what doesn't need pinn'd, and let her decide.
a b à CPUs
July 9, 2009 4:40:17 PM

Could be that the dual boot way would be better saves the extra power for the second drive if nothing else and makes booting into the OS easier i guess.
Im sure i can get her around sooner than later, i mean her laptop is running Vista for christs sake i really dont see what her problem is, but we need to keep them sweet.. Right :sweat: 

Mactronix
a b à CPUs
July 9, 2009 5:18:52 PM

mactronix said:
i really dont see what her problem is, but we need to keep them sweet.. Right :sweat: 



/agree From personal experience: Fail this at your peril... :cry: 
July 9, 2009 6:41:51 PM

mactronix said:
(like Mozilla Thunderbird for example which doesn't support 64 bit at this time)


Since when? I'm running 64-bit Thunderbird right now.
a b à CPUs
July 9, 2009 8:19:26 PM

MarkG said:
Since when? I'm running 64-bit Thunderbird right now.


Oh, ok well i will go look on the site again. When i looked last week there was no mention of a seperate 64 bit version and the version i downloaded said it didnt support a 64 bit OS when i installed it.

Mactronix
a b à CPUs
July 13, 2009 2:56:43 PM

Thanks for the heads up on the 64bit Thunderbird Mark, I now have it running also. Minus points for Mozilla for making it so difficult to find though.
From thier home page no chance, I had to actually search specifically for 64 bit Thunderbird on the net to find it.

Come on guys (yea i know they wont be reading this) get your act's together.

Seriously though its no wonder people are cautious about switching if even the apps that are 64 bit are so hard to find. Or was i expecting too much to get a choice of 32 or 64 from the home page ?

Mactronix
a b à CPUs
July 13, 2009 6:31:52 PM

mactronix said:
I'm assuming that there must be parts of the CPU that are dormant when running 32 bit ? so would this mean it uses more power in 64 bit mode. If so does is it enough for more volts when running an OC ?

Think of it like the difference between a 6-digit calculator and a 12-digit calculator. A 12-digit calculator may use more power than a 6-digit one, but if you've bought a 12-digit calculator do you think it uses any less power when you only put 6-digit numbers into it? No, not really.

mactronix said:
How does it affect things as far as the bandwidth goes ? again assuming the app is codded for 64 bit then its processing the data twice as fast, or is it just twice as much ? so what effect does this have if any on the buses ?

By far the biggest benefit of 64 bits is that a 64-bit application can use more memory. Any program that NEEDS lots of memory and is limited by the 2GB or 3GB available in 32-bit mode is going to have to do disk I/Os, and since it takes a million times longer to access data on disk than it does on RAM this has a huge performance impact. 64 bits removes the memory ceiling and (for the apps that need it) this is a much, much bigger benefit than anything else.

In terms of mere 64-bit calculations, they're few and far between, and since the performance penalty of splitting a 64-bit arithmetic operation into two 32-bit ones is a mere three-fold or so, it's really not worth thinking about. In a spreadsheet, for example, you'd likely be lucky if one in 100 instructions had to compute a 64-bit number. In 32-bit mode that would translate to the difference between 100 instructions vs. 102 instructions (one of those 100 is replaced by 3 instructions). So the overall effect is pretty negligible.

There may be some very specialized apps that are very 64-bit intensive, but most run-of-the mill stuff (including games, which offload most of the heavy crunching to the GPU), don't really benefit much at all from the 64-bit arithmetic capabilities of the CPU.
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