What is AGP aperture(sp?) size?

[TheCrackedJack]

on my bios it says 128 MB and I have a 32 MB card. What does that mean? In the manual, it says the amount of system memory dedicated to the AGP, what does that mean?

 

[Mr.IncrediblyBored]

Your video card has 32 megabytes of space to do its thing. In this 32 megabytes of space, it stores textures, polygons, lighting information, front/back/z-buffers, etc. This is essentially your video card's scratch pad to render the scene.

If a video game tries to store more than the video card can handle, it will spill the rest of the data over into your system memory (main RAM). The aperture (sic) size is the MAXIMUM alloted space that your video card can hijack from the system memory. If a particular scene requires 53 megabytes of space, approximately 32 megabytes of it will be stored on your video card. The rest of it will be stored in the system RAM.

Also, using your computer as an example, if a particular scene requires 177 megabytes of space, 32 MB of the data will go onto your video card, 128 MB will go into system RAM, and the remaining 17 MB will be written to the harddrive.

This doesn't take into account virtual texturing, texture/framebuffer/z-buffer compression, etc, etc. This is a simplified explanation, but you should get the idea.

 

[TheCrackedJack]

So I guess I should set it to 256MB, right?

 

[Mr.IncrediblyBored]

Originally posted by: TheCrackedJack
So I guess I should set it to 256MB, right?

Wouldn't hurt.

 

[zephyrprime]

Doesn't really matter. If you ever used a game that required the agp aperture space (known in directx as non-local video memory) you'd be screwed because it would be mind bogglingly slow.

 

[ScottMac]

Your best course (IMHO) would be to use a benchmark program....

Set the ap size, run the benchmark, set the size to the next value, run the benchmark, (repeat as necessary).

When you reach the point where speed / quality drops (or improves, depending on if you're going up or down in the vlaues), back up one notch.

The benchmark doesn't have to be 3Dmark, it can be your favorite game in demo mode, whatever you use the system for the most.

Values can be different for different systems, depending on the amount of RAM, , motherboard, disk, video card, drivers, the software ...

I believe that memory set aside for AGP aperature is also tagged for "no swap," which may affect the performance as well (again, depending on RAM, etc).

Good Luck

Scott