How much of my RAM that is reported can I actually use?

Hi :)

I have a W7 Ult SP-1 64-bit comp with 48 GB of RAM. Four 8 GB sticks, four 4 GB sticks.

Each 8 GB stick is actually 8192 instead of 8000 and each 4 GB stick is actually 4096 instead of 4000. This gives me 49093, according to the T.M. Slightly less than what it should be, but that's fine.

Q is - do I actually have 49 GB of RAM available to use? Not that I would push it to the last byte, but if I got up to, say, 48.5 GB - would that be an issue?

Thanks in advance.

When referring to RAM 1 GB is defined as 1024 * 1024 * 1024 or 1073741824 bytes. When dealing with disk space most manufacturers define 1 GB as 1,000,000,000 bytes. So you have 48 GB RAM.

riffwraith said:

Each 8 GB stick is actually 8192 instead of 8000 and each 4 GB stick is actually 4096 instead of 4000. This gives me 49093, according to the T.M. Slightly less than what it should be, but that's fine.

The sizes are correct, but to be strictly correct each stick is not 8GB, but 8 GiB. In computers, most measures are in multiples of 1024, not 1000, and those prefixes are know as Kibibyte. RAM sizes are all in GiB, not GB, but Windows always show them wrong, displaying GB when it should use GiB.
You're correct in that you have 49GB (more or less), but it's 48Gib and that's what Windows will show you. It's just a minor display bug.

riffwraith said:

Q is - do I actually have 49 GB of RAM available to use?

From the entire amount of installed physical memory, how much is actually useable by the OS depends on a number of factors. In your particular case I would say that yes, it's entirely available.

First of all comes hardware support. The motherboard must support all of it, both by providing enough slots and having support for counting and referencing it in the BIOS. The motherboard/processor/computer manual should specify the maximum amount of RAM (as well as its type) that it can handle, any more that that will be wasted.

Then comes hardware usage. Other devices on the computer can reserve small amounts of RAM for its own usage. Prime example of this are on-board video cards that have no dedicated video memory, which draw some main RAM for use for it. That memory will not be available for OS usage, but technically it's not wasted, just used somewhere else.

Then comes the OS limitations. Windows specifically imposes additional artificial restrictions on maximum RAM based on edition. Starter can use 2GB, Professional 4GB and so on. 32 bits versions also have an artificial limitation of 4GB.

A chart:
Memory Limits for Windows and Windows Server Releases (Windows)

Alejandro85 said:

riffwraith said:

Each 8 GB stick is actually 8192 instead of 8000 and each 4 GB stick is actually 4096 instead of 4000. This gives me 49093, according to the T.M. Slightly less than what it should be, but that's fine.

Then comes the OS limitations. Windows specifically imposes additional artificial restrictions on maximum RAM based on edition. Starter can use 2GB, Professional 4GB and so on. 32 bits versions also have an artificial limitation of 4GB.

Windows 7 64 bin has a limitation of 192 gb for enterprise, ultimate, and pro whereas it is 16 & 8 for home premium and basic. The 4 gb size for 32 is a mathematical limitation; what do you mean by artificial? As stated there is also a limitation on how much memory is actually supported by your system. If you exceed that anything else beyond that won't be available to the OS.

Memory Limits for Windows and Windows Server Releases (Windows)
64-bit computing - Wikipedia, the free encyclopedia

In reality I agree that more than likely you won't use anywhere near that so why waste your money?

townsbg said:

Windows 7 64 bin has a limitation of 192 gb for enterprise, ultimate, and pro whereas it is 16 & 8 for home premium and basic.

Ups yeah, my bad, I was putting the numbers from memory (about memory ), but the chart is correct.

townsbg said:

The 4 gb size for 32 is a mathematical limitation; what do you mean by artificial? As stated there is also a limitation on how much memory is actually supported by your system. If you exceed that anything else beyond that won't be available to the OS.

By artificial I mean that it's a limit arbitrarily set by Microsoft that obey no technical reason. The linked charts of memory limits are actually all artificial, they're set as they are just to lure people into buying the most expensive editions if they want to use more RAM, but the system is actually capable of handling more. The 4GB of x86 is also artificial, presumably to get people to migrate to x64.

townsbg said:

In reality I agree that more than likely you won't use anywhere near that so why waste your money?

I agree too. 48GB is an enormous amount. Few users will ever use that much memory, and even servers can waste some with that much. 4 or 8 is normally enough for most people. Of course, the actual use case of the OP might be different.

[QUOTE=Alejandro85;2925930]

townsbg said:

townsbg said:

The 4 gb size for 32 is a mathematical limitation; what do you mean by artificial? As stated there is also a limitation on how much memory is actually supported by your system. If you exceed that anything else beyond that won't be available to the OS.

By artificial I mean that it's a limit arbitrarily set by Microsoft that obey no technical reason. The linked charts of memory limits are actually all artificial, they're set as they are just to lure people into buying the most expensive editions if they want to use more RAM, but the system is actually capable of handling more. The 4GB of x86 is also artificial, presumably to get people to migrate to x64.

By your own definition the artificial limitation would apply to the 64 bit versions. Technically (not considering other aspects) a 64 bit OS should be able handle a lot more than even 192 gb. the 4 gb limitation is purely mathematical because 2 to the 32nd power is 4 gb. The 64 bit version is the same price as the 32 bit so your argument doesn't even make sense. The price difference is in the version (ie ultimate, pro, etc).