A quick and probably simple Memory question

[NickCapolupo]

I am currently running on windows 7 (32 bit). I have 2 X 2gb of Kingston HyperX memory. It says it registers as 4gb, but only 3.25 useable. I believe I read that this is because 32 bit windows can only handle 4gigs but has to accomidate video cars, etc..

Now, If I get windows 64 bit, will it use all 4gb of memory instead of 3.25?? (64 bit can handle way more than 4 gigs, right?

I just want to make sure Im getting maximum performance on my first build

 

[JDFan]

YOu are correct -- 32 bit OSes store the memory address in a 32 bit space so 2^32 is the maximum number of address spaces available (2^32 = 429,467,296 or 4GB.) From that there are the system reserved address spaces and Video Page file spaces (these are not exactly the same as the GPU memory amount so a 1gb. or 2gb. memory video card will not subtract 1gb. or 2 GB. of that useable space since the video card handles that memory and the system only uses the page files to interact with the video card) that are subtracted leaving Approx 3.25 GB of available addresses (will vary slightly depending on the system and configuration )

BUT that said you are still better off with 4GB. in a 32 bit system so that the memory modules can be run in dual channel mode instead of single channel even though it wastes .75 GB !

ALso the 64 bit Oses store the addresses in a 64 bit space so you then have 2^64 addresses or 18,446,744,073,709,551,616 -- so many times more spaces available

(Note the various OS versions themselves will have specific memory limits) which are as follows :

Here are the upper RAM limits for the different editions of Windows 7:

* Starter: 8GB
* Home Basic: 8GB
* Home Premium: 16GB
* Professional: 192GB
* Enterprise: 192GB
* Ultimate: 192GB

These limits are similar to those for Vista editions, expect that Vista Enterprise and Vista Ultimate have had their upper limits raised from 128GB to 192GB.

The one to look out for there is the 16GB limit on Home Premium. If you’re building a Core i7 system then it’s quite easy (if you have the cash!) to exceed this limit. As long as you’re aware of the limit and plan your OS accordingly you’ll be OK.

 

[MadCatz900]

64bit windows can handle more than 4gb.

http://msdn.microsoft.com/en-us/library/aa366778(VS.85).aspx#physical_memory_limits_windows_xp

 

[NickCapolupo]

"BUT that said you are still better off with 4GB. in a 32 bit system so that the memory modules can be run in dual channel mode instead of single channel even though it wastes .75 GB ! "

So you're saying to stick with the 32 bit windows 7 (Ultimate is what I have) and 3.25 useable, instead of going 64 bit? So I would no longer be using my memory in dual channel if I did? Sorry, that part confuses me a bit..

 

[JDFan]

No - IF you are buying a new OS then you should probably go with the 64 bit ( I say probably because it would depend on the other hardware\software you are using - and whether they all work in a 64 bit OS - some older hardware and software are not supported in a 64 bit OS so if you have things that would no longer work due to lack of drivers\support for them then go with the 32 bit OS.) also if you already have the 32 bit OS then it is not really worth paying $100+ just to move to a 64 bit OS just to get the use of that .75GB of RAM (if you were adding another 4GB to use 8GB total then you'd want to go to a 64 bit OS but for 4 GB. it is pretty much the same with either option.

The reason I mention dual channel is that the system will perform better by keeping the number of modules in pairs instead of say 3 1GB modules even though you only get .25GB of useable memory from that 4th module if using the 32 bit OS - so even with a 32 bit OS you'll still want the memory modules in pairs for better performance instead of just using the 3 modules and say selling the 4th but yes it will still be dual channel if you switch to the 64 bit OS using the 4GB. so no difference there.

What I was saying is that if you already have the 32 bit OS and are just thinking of paying for a new OS to get to use that extra .75GB. of memory - it is not worth the investment so just keep the 32 bit OS and use the 3.25 GB. out of 4GB. because you will not see much difference between the 2 (and even if you do not need to spend $ to make the change (IIRC win 7 comes with both versions on the same install disk) the time spent to backup everything and reformat\reinstall the OS and then all of your programs is not really worth the effort)

 

[NickCapolupo]

Oh ok. Well, here was my initial plan. I just built this computer maybe a week ago. EVERYTHING is brand new stuff, so I dont see having any problems with compatibility. I also wouldnt make the upgrade unless it is free (I got the 32 bit free from a friend, and plan on hunting down maybe another friend with the 64 bit version). And the fact that my computer is new (Dont even have the internet yet, will in about a month as Im a broke fool, thanks to spending more than i meant on the computer), there arent many files at all to back up and re-save, ya know? Because I see shortly down the future wanting 8gb of memory. So from what I gather, it would be a good idea for me to go ahead and upgrade to 64 bit now, as it wont cause me much grief/time to do. You have been very helpful

 

[NickCapolupo]

Best answer selected by NickCapolupo.

 

[JDFan]

In that set of circumstances then YES going to the 64 bit OS is probably better done now rather than going through the hassle later when you do decide to go to the 8GB.. after installing a bunch of other programs and getting them set up the way you want it becomes much more of a hassle to reformat\reinstall everything !