Tag Archives: DVMT

DVMT Mode from The Tech ARP BIOS Guide

DVMT Mode from The Tech ARP BIOS Guide

DVMT Mode

Common Options : Fixed, DVMT, Both

 

Quick Review of DVMT Mode

Unified Memory Architecture (UMA) is a concept whereby system memory is shared by both CPU and graphics processor. While this reduces cost, it also reduces the system’s performance by taking up a large portion of memory for the graphics processor.

Intel’s Dynamic Video Memory Technology (DVMT) takes that concept further by allowing the system to dynamically allocate memory resources according to the demands of the system at any point in time. The key idea in DVMT is to improve the efficiency of the memory allocated to either system or graphics processor.

The BIOS feature that controls all this is the DVMT Mode BIOS feature. It allows you to select the DVMT operating mode.

When set to Fixed, the graphics driver will reserve a fixed portion of the system memory as graphics memory. This ensures that the graphics processor has a guaranteed amount of graphics memory but the downside is once allocated, this memory cannot be used by the operating system even when it is not in use.

When set to DVMT, the graphics chip will dynamically allocate system memory as graphics memory, according to system and graphics requirements. The system memory is allocated as graphics memory when graphics-intensive applications are running but when the need for graphics memory drops, the allocated graphics memory can be released to the operating system for other uses.

When set to Both, the graphics driver will allocate a fixed amount of memory as dedicated graphics memory, as well as allow more system memory to be dynamically allocated between the graphics processor and the operating system.

It is recommended that you set this BIOS feature to DVMT for maximum performance. Setting it to DVMT ensures that system memory is dynamically allocated for optimal balance between graphics and system performance.

 

Details of DVMT Mode

Unified Memory Architecture (UMA) is a concept whereby system memory is shared by both CPU and graphics processor. While this reduces cost, it also reduces the system’s performance by taking up a large portion of memory for the graphics processor.

Intel’s Dynamic Video Memory Technology (DVMT) takes that concept further by allowing the system to dynamically allocate memory resources according to the demands of the system at any point in time. The key idea in DVMT is to improve the efficiency of the memory allocated to either system or graphics processor.

To ensure better allocation of system memory, DVMT comes with three different operating modes :

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  • Fixed Memory
  • DVMT Memory
  • Fixed + DVMT Memory

But before we go into the details of each mode, it’s important to note that the system boots up with some system memory pre-allocated for graphics, irrespective of the DVMT operating mode. Depending on the motherboard manufacturer, you may or may not be allowed to select between a choice of 1MB or 8MB of pre-allocated memory.

This pre-allocated memory is dedicated to VGA/SVGA graphics and will be treated by the operating system as dedicated graphics memory. This pre-allocated memory will not be visible or accessible to the operating system. It will be used during the booting process to display the boot and splash screens, or when you run MS-DOS games and applications. It will also be used when Windows XP loads in Safe Mode.

Once an operating system with the appropriate Intel Graphics Media Accelerator Driver loads up, the graphics processor reclaims the pre-allocated memory for its use. But again, it is only available for use as graphics memory. It will never be made available to the operating system or applications. The Intel GMA driver then loads additional system memory according to the DVMT operating mode.

The Fixed Memory operating mode reserves a fixed amount of system memory as graphics memory. This is in addition to the memory already pre-allocated. Like pre-allocated memory, this fixed amount is no longer available to the operating system. But when the operating system reports the total system memory, it will include this amount, as opposed to pre-allocated memory.

The DVMT Memory operating mode allows the graphics driver to dynamically allocate system memory for use by the graphics processor. When no graphics-intensive operations are occuring, most of the DVMT memory can be reallocated to the operating system for other uses. When more graphics memory is required, the graphics driver will automatically reallocate more system memory for use as graphics memory.

The Fixed + DVMT Memory operating mode is an combination of the Fixed and DVMT operating modes. It allows you to allocate a fixed amount of reserved graphics memory (over the minimum pre-allocated amount), as well as a portion of system memory that can be dynamically allocated to both graphics processor and operating system.

This figure from Intel clearly shows the differences between the three different DVMT operating modes :

The BIOS feature that controls all this is the DVMT Mode BIOS feature. It allows you to select the DVMT operating mode.

When set to Fixed, the graphics driver will reserve a fixed portion of the system memory as graphics memory. This ensures that the graphics processor has a guaranteed amount of graphics memory.

But the downside is, once allocated, this memory cannot be used by the operating system even when it is not in use. Usually, the following configuration scheme is used :

System Memory DVMT Graphics Memory
Pre-Allocated Fixed Total
128 – 255 MB 1 MB 31 MB 32 MB
8 MB 24 MB
256 – 511 MB 1 MB 63 MB 64 MB
8 MB 56 MB
1 MB 127 MB 128 MB
8 MB 120 MB
512 MB and larger 1 MB 63 MB 64 MB
8 MB 56 MB
1 MB 127 MB 128 MB
8 MB 120 MB

When set to DVMT, the graphics chip will dynamically allocate system memory as graphics memory, according to system and graphics requirements. The system memory is allocated as graphics memory when graphics-intensive applications are running.

But when the need for graphics memory drops, the allocated graphics memory can be released to the operating system for other uses. Usually, the following configuration scheme is used :

System Memory DVMT Graphics Memory
Pre-Allocated Fixed Total
128 – 255 MB 1 MB 31 MB 32 MB
8 MB 24 MB
256 – 511 MB 1 MB 63 MB 64 MB
8 MB 56 MB
1 MB 127 MB 128 MB
8 MB 120 MB
1 MB 159 MB 160 MB
8 MB 152 MB
512 MB and larger 1 MB 63 MB 64 MB
8 MB 56 MB
1 MB 127 MB 128 MB
8 MB 120 MB
1 MB 223 MB 224 MB
8 MB 216 MB

When set to Both, the graphics driver will allocate a fixed amount of memory as dedicated graphics memory, as well as allow more system memory to be dynamically allocated between the graphics processor and the operating system. Usually, the following configuration scheme is used :

System Memory DVMT Graphics Memory
Pre-Allocated Fixed Total
128 – 255 MB NA
256 and larger 1 MB 63 MB + 64 MB 128 MB
8 MB 56 MB + 64 MB

It is recommended that you set this BIOS feature to DVMT for maximum performance. Setting it to DVMT ensures that system memory is dynamically allocated for optimal balance between graphics and system performance.

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FIXED Memory Size – The Tech ARP BIOS Guide

FIXED Memory Size

Common Options : 0 MB, 32 MB, 64 MB, 128 MB

 

Quick Review of FIXED Memory Size

Unified Memory Architecture (UMA) is a concept whereby system memory is shared by both CPU and graphics processor. While this reduces cost, it also reduces the system’s performance by taking up a large portion of memory for the graphics processor.

Intel’s Dynamic Video Memory Technology (DVMT) takes that concept further by allowing the system to dynamically allocate memory resources according to the demands of the system at any point in time. The key idea in DVMT is to improve the efficiency of the memory allocated to either system or graphics processor.

The FIXED Memory Size BIOS feature is used in conjunction with the DVMT Memory Size BIOS feature to select the operating mode as well as the maximum amount of graphics memory that can be allocated to the onboard graphics processor.

When DVMT Memory Size is set to 0MB and this BIOS feature set to 32 MB, a total of 32 MB of system memory is allocated as graphics memory in the Fixed mode.

When DVMT Memory Size is set to 0MB and this BIOS feature set to 64 MB, a total of 64 MB of system memory is allocated as graphics memory in the Fixed mode.

When DVMT Memory Size is set to 0MB and this BIOS feature set to 128 MB, a total of 128 MB of system memory is allocated as graphics memory in the Fixed mode.

If DVMT Memory Size is set to any value other than 0 MB, then the onboard graphics processor will operate in the Fixed + DVMT Memory mode. This would be based on the total memory size allocated to both DVMT Memory Size and FIXED Memory Size.

For example, if you set DVMT Memory Size to 64 MB and FIXED Memory Size to 64 MB, the total graphics memory size would be 128 MB. But the actual allocation of graphics memory would depend on the amount of pre-allocated graphics memory.

Generally, it is recommended that you let the graphics driver allocate memory in DVMT mode. This allows the driver to dynamically allocate memory according to changing situations. This means setting this BIOS feature to 0 MB and setting the maximum graphics memory size using the DVMT Memory Size BIOS feature. It’s advisable to restrict the total graphics memory to approximately 256 MB for systems with lots of memory (768 MB or more) and reduce the graphics memory in systems with less memory.

 

Details of FIXED Memory Size

Unified Memory Architecture (UMA) is a concept whereby system memory is shared by both CPU and graphics processor. While this reduces cost, it also reduces the system’s performance by taking up a large portion of memory for the graphics processor.

Intel’s Dynamic Video Memory Technology (DVMT) takes that concept further by allowing the system to dynamically allocate memory resources according to the demands of the system at any point in time. The key idea in DVMT is to improve the efficiency of the memory allocated to either system or graphics processor.

To ensure better allocation of system memory, DVMT comes with three different operating modes :

  • Fixed Memory
  • DVMT Memory
  • Fixed + DVMT Memory

For more details on the individual operating modes, please take a look at the DVMT Mode BIOS feature.

Before we go further, it’s important to note that the system boots up with some system memory pre-allocated for graphics. Depending on the motherboard manufacturer, you may or may not be allowed to select between a choice of 1 MB or 8 MB of pre-allocated memory.

This pre-allocated memory is dedicated to VGA/SVGA graphics and will be treated by the operating system as dedicated graphics memory. This pre-allocated memory will not be visible or accessible to the operating system. It will be used during the booting process to display the boot and splash screens, or when you run MS-DOS games and applications. It will also be used when Windows XP loads in Safe Mode.

Once an operating system with the appropriate Intel Graphics Media Accelerator Driver loads up, the graphics processor reclaims the pre-allocated memory for its use. But again, it is only available for use as graphics memory. It will never be made available to the operating system or applications. The Intel GMA driver then loads additional system memory as required.

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The FIXED Memory Size BIOS feature is used in conjunction with the DVMT Memory Size BIOS feature to select the operating mode as well as the maximum amount of graphics memory that can be allocated to the onboard graphics processor.

When DVMT Memory Size is set to 0MB and FIXED Memory Size set to 32MB, up to 32 MB of system memory is allocated as graphics memory in the DVMT mode. This is usually allocated as below :

DVMT Graphics Memory

Pre-Allocated

Fixed

Total

1 MB

31 MB

32 MB

8 MB

24 MB

When DVMT Memory Size is set to 0MB and this BIOS feature set to 64MB, up to 64 MB of system memory is allocated as graphics memory in the DVMT mode. This is usually allocated as below :

DVMT Graphics Memory

Pre-Allocated

Fixed

Total

1 MB

63 MB

64 MB

8 MB

56 MB

When DVMT Memory Size is set to 0MB and this BIOS feature set to 128MB, up to 128 MB of system memory is allocated as graphics memory in the DVMT mode. This is usually allocated as below :

DVMT Graphics Memory

Pre-Allocated

Fixed

Total

1 MB

127 MB

128 MB

8 MB

120 MB

If DVMT Memory Size is set to any value other than 0MB, then the onboard graphics processor will operate in the Fixed + DVMT Memory mode. This would be based on the total memory size allocated to both DVMT Memory Size and FIXED Memory Size.

For example, if you set DVMT Memory Size to 64MB and FIXED Memory Size to 64MB, the total graphics memory size would be 128 MB. But the actual allocation of graphics memory would depend on the amount of pre-allocated graphics memory. Usually, it would be allocated as below :

DVMT Graphics Memory

Pre-Allocated

Fixed

Total

1 MB

63 MB + 64 MB

128 MB

8 MB

56 MB + 64 MB

Please note that this BIOS feature only restricts the maximum amount of system memory that can be allocated as graphics memory in DVMT mode. The graphics driver will determine the actual amount of system memory requisitioned, up to the maximum set. In addition, DVMT graphics memory can be re-allocated to the operating system when there are no graphics-intensive applications running.

Generally, it is recommended that you let the graphics driver allocate memory in DVMT mode. This allows the driver to dynamically allocate memory according to changing situations. This means setting the FIXED Memory Size BIOS feature to 0MB and setting the maximum graphics memory size using this BIOS feature.

It’s advisable to restrict the total graphics memory to approximately 256 MB for systems with lots of memory (768 MB or more) and reduce the graphics memory in systems with less memory.

Go Back To > The Tech ARP BIOS Guide | Home

 

Support Tech ARP!

If you like our work, you can help support our work by visiting our sponsors, participating in the Tech ARP Forums, or even donating to our fund. Any help you can render is greatly appreciated!