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Frequently Asked Questions about Older Intel® Graphics Products Memory


Last Reviewed: 09-Jan-2017
Article ID: 000006532

Note For newer Intel® graphics products, refer to Graphics Memory FAQ For Windows 8 and 8.1*.
 

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What is dynamic video memory technology (DVMT)?

DVMT is a concept used with Intel® graphics products where the optimum amount of memory is dynamically allocated and de-allocated as needed for balanced 2D/3D graphics and system performance. DVMT allocates the proper amount of display, texturing, and buffer memory after the operating system has booted. The operating system views the Intel® Graphics Media Accelerator Driver as an application, which uses Intel® direct AGP to request allocation of additional memory for 3D applications. It returns the memory to the operating system when no longer required.

What are the benefits of DVMT?

DVMT ensures the most efficient use of available system memory resources for maximum 2D/3D graphics performance.

DVMT aligns with Microsoft's "good driver" design guidelines. It dynamically uses only the system memory needed and returns these resources to the operating system when finished. Some integrated graphics solutions waste memory, as they permanently allocate large amounts of memory for dedicated use.

What is pre-allocated memory?

Pre-allocated memory is the small amount of system memory made available at boot time by the system BIOS for video. Pre-allocated memory is also known as locked memory. It's "locked" for video use only and invisible to the operating system.

Older Intel® graphics products allow for pre-allocated memory in the system BIOS to be set to 1 MB, 8 MB, or 16 MB. You shouldn't use the 512 KB legacy setting. Upon boot, the System BIOS pre-allocates the amount selected (1 MB or 8 MB) from the top of the main system memory, which will be dedicated for VGA/SVGA graphics.

Who sets pre-allocated memory?

The system manufacturer sets amount of pre-allocated memory via the system BIOS. Depending on the system BIOS implementation, the amount may or may not be configurable.

How do I determine/choose pre-allocated memory size?

512 K setting:

  • Provided as a legacy setting only and should not be used

1 MB setting:

  • Allows most memory resources to go to the operating system while allowing BIOS for all modes

8 MB setting:

  • Allows for a good balance between BIOS- and operating system-required memory resources for a typical 128 MB memory system
  • Enables booting of Microsoft* operating systems in as much as 1600x1200x32 mode without the driver having to ask the operating system for more memory


16 MB setting:

  • Maximum amount allowable, and is not available on all configurations
  • Should only be selected on systems with over 2456 MB of system memory.

Both the 512K and 1 MB settings assume the system is booting using a Microsoft* operating system.

What if an application requires more than the total amount of pre-allocated memory?

In systems using older Intel® graphics products, if a graphics-intensive application (a game, a DVD, etc.) requires more memory than the amount of pre-allocated video memory, it communicates that need to the Intel® Graphics Media Accelerator Driver. DVMT then asks the operating system to supply the extra memory required. When the application no longer requires the extra memory, DVMT returns it to the operating system. The memory can be used again as system memory.

What is the relationship between pre-allocated memory, the Intel® Graphics Media Accelerator Driver, DVMT, a Microsoft* operating system, and applications?

In systems using older Intel® graphics products, if a graphics-intensive application (a game, a DVD, etc.) requires more memory than the amount of pre-allocated video memory, it communicates that need to the Intel® Graphics Media Accelerator Driver. DVMT then asks the operating system to supply the extra memory required. When the application no longer requires the extra memory, DVMT returns it to the operating system. The memory can be used again as system memory.

When is DVMT triggered?

DVMT is triggered any time an application needs video memory above the pre-allocated amount. It is triggered again when an application no longer requires the extra memory and the memory must be returned to the operating system.

DVMT may also be triggered at boot time if you set a screen resolution requiring more memory than the total pre-allocated memory amount.

Will DVMT always get the memory requested?

DVMT may not always get the memory requested. The operating system decides if the request for more memory is granted or not. DVMT allows the operating system to decide based on availability of system memory resources and other requests it receives.

How much graphics memory does DVMT use?

The term "graphics memory size" is the same as "memory size" in the Control Panel/Display Adapter pages or "video memory" used by external PCI Express* graphics cards. It's the memory dedicated for graphics for the time that the application is active and the operating system has granted the requested memory.

Memory size = Pre-allocated memory extra memory requested by the application via the Intel® Graphics Media Accelerator Driver.

The maximum amount of graphics memory depends on the computer's System BIOS configuration. In most cases, the total does not exceed 128 MB. On some older computers, the system BIOS doesn't limit the graphics memory to 128 MB. You may see maximum graphics memory up to 224 MB.

Pre-allocated memory is invisible to the operating system. The extra memory requested by the application is relinquished back to the operating system upon exit by the Intel® Graphics Media Accelerator Driver.

 
Extra DVMT documents
Intel® 810 and 815 Chipset Family DVMT (PDF)
Intel® 82845G Graphics Controller DVMT (PDF)
Intel® 865G Graphics and Memory Controller Hub (GMCH) DVMT (PDF)
Intel® 915GM/GMS, 910GML Express Chipset Family
 

Note: PDF files require Adobe Acrobat Reader*

 
Related topics
Frequently asked questions about graphics memory for Windows 8*/8.1*
Frequently asked questions about graphics memory for Windows 2000*/XP*/Vista*/7*