Tweak3D.net - AGP Aperture Size Examined

Posted: August 29, 2002
Written by: Kayron James Mercieca and Dan "Tweak Monkey" Kennedy.

Conclusion

The results of these tests are less than conclusive, however, they do help in making suggestions and statements about the AAS. AGP sidebanding requires a minimum of 16 MB to work correctly, and this is probably why the crashing occurs below 16 MB on some tests (and reduced performance on others). As a new rule of thumb, never set the AAS below 16 MB, as performance and stability will be compromised. Another rule of thumb is that you should always set AAS to either be less than or equal to your total system memory, as you cannot use memory you do not have in the first place.

Performance is nearly identical from 16 to 256 MB, with minor dips at 64 MB AAS and problems with 256 MB on the GeForce3 Ti500 card. With new games coming out all the time that push our PCs to the limit, it might be a good idea to try and run a higher AGP aperture size, to be sure you’ve allocated enough memory for the video card. For this reason, we suggest at least a 128 MB AAS unless system memory is very low, or problems are experienced.

Ideally, you’d want to run a 256 MB AAS, as it would result in the best video performance and compatibility. As our tests showed though, 256 MB AAS does not work on all PCs and configurations, so it must be tested. You should run an AAS of 256 MB on your system if you do not experience problems and you have the memory to spare (or you do not notice problems with applications hogging your memory). Remember that even if you have a 256 MB aperture size set, it is highly unlikely that you’ll use nearly 256 MB of memory at a time.

Other Information

Written by: Kayron James Mercieca, guest writer to Tweak3D.
Homepage(s): http://www.geocities.com/mrewebsite/ & http://www.geocities.com/opfmapping/.
Additional writing and editing by Dan "Tweak Monkey" Kennedy.

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