I see this question constantly being posted in forums.
Your AGP Aperature is said to be set at half your memory. However, I disagree with this. Most of the time you won't be able to go above 128MB without your computer freezing on you.
Keep your Aperature at the default for most boards which is 64MB.
If you experience locks-up or your computer freezes when playing video or using a video editing/capture program, then set it to 32MB.
You should really only play with the setting if your experiencing this problem.
Hope this helps.
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