Graphics card system RAM requirements

northlondon01 · 17 Feb 2014

Hi all,

I'm looking to get a new card - maybe a 7870, 270 or 270X and I was wondering about the system requirements, and they often say 4GB RAM.

My mobo can only take 4GB (and gives me just under as usable system RAM) and I can't get the mobo to allow more than 4GB even when I tried 64bit W7 (I've got 32bit W7 Ultimate at the moment).

If I got a 2GB card, how would this work with my system? Would I not be able to use the 4GB system RAM and the 2GB graphics card RAM, or is this separate (I didn't think they were!)? What does the 4GB minimum in the system requirements relate to? Wouldonly having slightly less than 4GB, or not being able to use more than 4GBt cause problems etc?

Any advice, as ever, greatly appreciated!

badger906 · 17 Feb 2014

Windows 32bit limits to a maximum of 4gb ram, thats everything that has RAM. so youll only have 2gb of system ram and 2gb GPU ram.

Any game that will push a 270x to its limits will use waaaaaaaay more than 2gb of ram so that will be your bottle neck. 4gb isnt exactly enough for most intensive games if you have anything running in the back ground.

northlondon01 · 17 Feb 2014

Thanks badger!

Can you just confirm that if my mobo can only 'handle' 4GB of RAM (there's no option to change this in the BIOS unfortunately) and I have a 2GB graphics card my system will only be using 2GB of each, even with a copy of 64bit W7 (I have one from work I can use, but planned on saving it for when I get a new mobo etc)? Or would having 64bit W7 allow me to use 4GB and 2GB, regardless of the mobo restrictions? I think it's the former!

Thanks again.

badger906 · 17 Feb 2014

theres nothing you can do to increase your mobos maximum ram capacity, unless there was a bios update addressing it but I highly doubt that. but that doesnt include peripherals such as gpus.

yes win 32 will limit you to a MAX of 4gb this includes gpu and sound card and any other devices with ram bufferes such as dvd drives and soundcards ect.

win 64bit starter and home basic edition allow upto 8gb, home premium 16gb and professional and ultimate 192gb.. yeah try maxing that out.

you could always search ebay for an old used lga 775 motherboard and replace yours allowing you to add some more ram!!

RoasterMen · 18 Feb 2014

badger906 said:

Windows 32bit limits to a maximum of 4gb ram.

It limits 3.5GB of ram in some cases. If you have a 4GB of ram with 64-bit OS installed, most likely it will only take 3.8GB of ram.

madcratebuilder · 18 Feb 2014

Limits on memory and address space

This MS paper should help explain shared memory mapping.

Layback Bear · 18 Feb 2014

Foxconn PRODUCT : Motherboard : Details

LMiller7 · 18 Feb 2014

A 32 bit OS has a fixed 4 GB physical address space. Most of this space is available for RAM but it must also be shared with memory mapped hardware devices. Memory mapping is a quick way for the CPU to communicate with hardware devices, essential for audio and video. Note that we are talking about address space, where RAM can be located, not RAM usage itself. Space used for memory mapped IO reduces that available for RAM. Typically this will allow space for about 3.25 GB RAM but it can be more or less. With 3 GB RAM or less there is usually ample room for everything and almost all RAM can be accessed.

If the video card has it's own RAM it does not appear in the CPU's address space so it doesn't effect RAM availability. But space for mapping will still be required. But many inexpensive video systems (very common in laptops) have little or no RAM of their own so all of their requirements must come from system RAM.

64 bit systems have a much larger address space so there is room for 4 GB or more RAM and everything else with no conflict. Of course if the video system requires system RAM to operate that will be subtracted from that available to Windows.