DVMT (Dynamic Video Memory Technology) systems share system memory causing increased bus traffic to/from the GMCH (graphics and memory controller hub) and system memory. In summary, faster memory = performance gains.
- PC100 = single data rate memory at 100 MHz
Bandwidth = 64bit x 100 MHz / (8bits/byte) = 800 MB/sec
- PC133 = single data rate memory at 133 MHz
Bandwidth = 64bit x 133MHz / (8bits/byte) = 1064 MB/sec
- DDR200 = double data rate memory at 200 MHz (100 MHz x 2)
Bandwidth = 64bit x 200 MHz / (8bits/byte) / (1024 MB/GB) = 1.6 GB/sec
- DDR266 = double data rate memory at 266 MHz (133 MHz x 2)
Bandwidth = 64bit x 233 MHz / (8bits/byte) / (1024 MB/GB) = 2.01 GB/sec
- DDR333 = double data rate memory at 333MHz (166 MHz x 2)
Bandwidth = 64bit x 333 MHz / (8bits/byte) / (1024 MB/GB) = 2.60 GB/sec
- Dual Channel DDR400= double data rate memory at 400 MHz (200 MHz x 2)
Bandwidth = 64bit x 400 MHz x 2 channels / (8bits/byte) / (1024 MB/GB) = 6.25 GB/sec
For example, upgrading an Intel® 82845G/GL graphics controller-based system using DDR200 memory to DDR266 memory results in about 600 MB/sec of additional bandwidth.
Advantages of DVMT
The result is less total system memory is required to perform a wide range of operations and the 32 MB of video memory is used.
Textures and other items are already in the main system memory increasing efficiency of memory usage and generating less AGP bus traffic
DVMT memory allocations with various graphics controllers:
Intel® 82915G graphics controller
Intel® 82865 graphics controller
Intel® 82852/82855 graphics controller
Intel® 82845 graphics controller
This applies to: