What does AGP Aperture size do?

[Tim]

I was running a 3DMark05 test on my PC tonight, and in the details of my system, I noticed my AGP aperture size was at 53 MB according to 3DMark05. In the BIOS it was at 64 MB.

I was wondering what AGP aperture is, and what's a good amount of RAM to have it set to? I've thought of it in the past, but got distracted on some other topic before getting here to write a question about it.

I'm going to set it to 512 MB (BIOS max), and rerun the test.

[Tim]

3DMark05 at 64 MB AGP Aperture:

2969 3DMarks
3124 CPU Marks

512 MB AGP Aperture:

2987 3DMarks
3155 CPU Marks

This is on an Abit NF-7 Version 2.0, XP2500+ at 2.2 Ghz (11X200), 1.25 GB RAM, and a Radeon X700 Pro video card.

I just got an X850 Pro and will be installing it tonight or tomorrow. Then retest it!

[Thrax]

It allows the video card to utilize more RAM. Typically this setting has no real effect.

[Tim]

Yes, I got the X850 installed with 7.7 drivers (8.5 and 8.7 drivers locked up the pc on a blue screen), and ran the 3DMark05 and 3DMark06 tests.

There was some slight test-to-test variation in the scores, but they were generally right about the same. No significant differences from different AGP aperture sizes.

Scores:

Radeon X700 Pro 256 MB on 6.14 drivers:

3DMark05 512 MB AGP aperture - 2987 3DMarks, 3155 CPU Marks.
3DMark06 same setup - 875 3DMarks, 425 SM 2.0 score, 773 CPU score.


Radeon X850 Pro 256 MB on 7.7 drivers:

3DMark05 512 MB AGP aperture - 5151 3DMarks, 3123 CPU Marks.
3DMark06 same setup - 1663 3DMarks, 865 SM 2.0 score, 780 CPU score.