System RAM reduced with new GC Installed

Max Dread · Post by **Max Dread** » Sat Sep 27, 2008 2:56 am

Hi all

Since installing my 9600GT 512 MB, I've noticed my system RAM in "System Properties" has gone from 3.24 to 2.99GB (I have 4GB installed). This makes sense because my previous card was 256MB...

What I don't know is what effect this will have on my system performance? I need as much RAM as possible because I mainly use my PC for music and have some RAM intensive software.

Before buying the card I was aware that this might be an issue. But I was told that my mobo (Intel DP35DP) should be able to "remap" memory allocation and therefore the GC would not effect the amount of RAM Windows sees.

So does anyone round here no more about this issue than me? Can anyone shed any light on it?

Cheers

Max

FartingBob · Post by **FartingBob** » Sat Sep 27, 2008 4:23 am

You really shoudlnt notice anything at all different. I dont think any 32bit windows apps can use 3GB anwyay, so unless you run multiple instances of the most RAM intensive apps you have you should be fine.

sjoukew · Post by **sjoukew** » Sat Sep 27, 2008 11:25 am

Windows 32 bit has 4gb address space. All memory mapped IO is also mapped in this address space, at the top of it. Almost all hardware uses memory mapped IO. Your vga card has more memory, so it needs more address space, so there is less address space for your ram.

There are two things you can do about it, use linux, which can address more ram in 32 bit than windows 32 bit, or use a 64 bit windows.

Mr. Perfect · Post by **Mr. Perfect** » Sat Sep 27, 2008 12:48 pm

I haven't fooled around with it myself, but there are a couple of articles about the 32bit ram barrier at Dan's Data.

He has other articles about the issue, including one where he talked about remapping memory holes, if you use the search feature on his site.

Max Dread · Post by **Max Dread** » Sun Sep 28, 2008 12:10 am

Thanks guys...

From what I understand, some mobos allow the IO devices to be re-mapped to an area above the 4gb line, therefore leaving more available for Windows. I have an Intel DP35DP mobo but have not benn unable to ascertain whether this has memory remapping or not, although I will keep looking into this.

However, I have another related question. Is it possible to somehow change my GC's RAM from 512mb to 256mb, by somehow disabling some of the RAM? I could then use it as a 256mb card in my DAW partition (with the /3gb switch enabled), and a 512mb card in my gaming partition. Something tells me it wont be possible, but I thougt it was worth an ask!!!

Cheers

Max

Lawrence Lee · Post by **Lawrence Lee** » Sun Sep 28, 2008 12:55 am

The amount of usable RAM varies - I don't know why some boards handle re-mapping better than others. With only a 128MB video card installed (and no other peripherals) I've seen 4GB turn into 2.5GB, 3.0GB, 3.5GB, and 3.64GB usable on 4 different boards. Check in the BIOS if the re-map function is enabled.

And no, you can't disable any of your video card's memory.

sjoukew · Post by **sjoukew** » Sun Sep 28, 2008 11:13 am

Max Dread wrote:Thanks guys...

From what I understand, some mobos allow the IO devices to be re-mapped to an area above the 4gb line, therefore leaving more available for Windows. I have an Intel DP35DP mobo but have not benn unable to ascertain whether this has memory remapping or not, although I will keep looking into this.

In theory this works, in practice it only works if all hardware drivers are using more then 32 bits for the memory addressing. Microsoft "discovered" that this wasn't / isn't the case. This did lead to a lot of issues and almost all 32 bit drivers which should be rewritten to get this feature working.
Microsoft chose to let windows remap the Memory addresses, but it is keeping all mapped addresses within the 32 bit boundary, so all 32 bit drivers do work.
If you enable memory remapping, it isn't going to give you more address space.