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Memory bandwidth
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
- Cost
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.
- Efficiency
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:
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