Can someone explain this please ( Shared Video Memory )

[neoglow]

Can someone explain the image below to me and what each heading for Memory means?

As you can see, its a GTX 460 with 1gb RAM onboard. The motherboard is an ASUS P8P67 Pro (with no onboard gfx) Socket 1155 and i5 2500k CPU and I have 4gb system RAM.

I had always assumed with desktop motherboards (not laptops) that the gfx card RAM was separate to system RAM and not shared, I have looked through the BIOS but cannot find anything related to RAM and gfx card sharing settings.

Is this normal or should there be no shared memory on an up to date rig?

Im running Vista 64bit.

Many Thanks.

***Heres a pic from XP, it seems only shared memory is in Vista or Win7.

 

[neoglow]

Windows automatically allocates a certain amount of system memory to be used by the graphics card as required.

As long as the GPU doesn't need more than 1024MB then the shared memory won't be used.

In your case 1024MB dedicated VRAM + 1780 of system RAM = 2804MB available in total.

So these values cannnot be changed and it is Windows that determines how much system memory will be shared to top up the gfx memory?

 

[neoglow]

Thanks for replies guys.

I think I found my answer after searching Google, its something to do with the behaviour of Vista (and presumably Win7) over Win XP and how memory is allocated depending on rig specs.

See this thread - http://www.tomshardware.co.uk/forum/233624-34-disabling-shared-system-memory

As quoted on the thread, this text was taken from the microsoft document which is available here - http://download.microsoft.com/download/9/c/5/9c5b2167-8017-4bae-9fde-d599bac8184a/GraphicsMemory.doc

In WDDM, the operating system can accurately account for each of the graphics memory contributors and report available memory precisely through new APIs. The following are some of the clients that use this reporting:

Windows System Assessment Tool (WinSAT) checks for the available graphics memory and takes the action to turn off or on the Premium Aero Glass experience based on the amount of available memory.

The Desktop Windows Manager (dwm.exe) is depends on the exact state of the available graphics memory on WDDM systems.

DirectX games and other graphics applications for Windows Vista need to be able to get accurate values describing the state of the graphics memory in the system. An inaccurate graphics memory number could drastically change the game experience for the user, for example.

Thus, Windows Vista enables the critically important capability of reporting the correct amount of graphics memory to the end-user.

 

[neoglow]

I just looked up the shared memory in XP, heres a pic. No shared memory is shown so I guess its only a feature of Vista or Win 7.