FIXED Memory Size – The Tech ARP BIOS Guide

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.

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.

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