There was a discussion on this a while back. Basically, what was learned in practical terms from it
was
Bottom line.
If your games run smoothly, dont do anything
If you see pauses, try lowering and increasing the aperture one notch, and see which clears the
problem. Which one works will depend on whether
1. You have set a big aperture and the card is being 'lazy' and actually using it - it will load
larger chunkis into the aperture and this causes bigger pauses than if you kept the aperture modest
(64M seems to be the sweet spot )
2. You have set a low aperture and this is causing the card problems because it is having to ask the
OS to load textures from hard drive
3. The probles is something else - see below
Having 1Mb of memory is the standard for smooth gaming, so if you cant get rid of the pauses with
AGP, you probably need more main memory.
If you are OCing and this causes you to start seeing glitches/pauses, it is probably due to bad
packets and not the AGP aperture. In this case, try upping the AGP voltage ***But be mindful that
this causes more heat in the card, and 9700 pros and 9800 pros run very hot as it is - you should
not try this with the stock cooling heatsink***
Commentry.
Getting the card to use the aperture is a work around to the fact that the card doesnt have enough
memory to save all the textures it needs in its own memory. This is normally something you do not
want to happen, so you dont want the aperture used at all if you can help it
In any case, the AGP aperture simply limits the maximim size the card will use (it has to be a
contigious block of memory, which is all the aperture really is - a request to the mobo to be in a
position to make xxMB of contigious memory be available if it is ever needed by the GFX. you dont
'lose' the memory by setting a high AGP, because it can be used by the OS until it is actually
claimed.... although setting a high AGP can have issues of its own
Details.
1. The only thing that the AGP aperture really affects is the level of those annoying pauses and
'dropped frame glitches' that you occasionally see in games. these can be caused by the card loading
textures in game (or rather, swapping textures from the aperture into its own memory).
2. Most modern cards (128Mb) dont have this issue, so AGP aperture doesnt actually do anything,
because the card doesnt need to load textures in game often (if at all - it can usually do it
between levels).
3. for the few games that have no levels (such as Operation Flashpoint and lock-on, both of which
just have one big terrain), experience shows that setting the AGP *low* to about 64M gives least
pausing, possibly because it stops the card using the aperture to load big chunks, instead forcing
it to load modest amounts more often. Obviously then, results per game vary slightly, because the
issue is partly affected by the game engine and how/when it requests textures through its API
(directX or OGL).
4. Doom3 seems to be the first game that really trashes the on board memory of current video cards.
On very high settings, it is recommended to have 512M of on board GFX memory, something that current
cards obviously dont have. The aperture will therefore be used heavily in such games, and you might
actually have to increase the aperture to reduce pauses. I havent played the game yet, so cant say,
although I suspect that the better option wil be to reduce the texture quality via game settings.
Ignoring Doom for a moment, AGP settings dont seem to have any real effect above 64M for 128Mb
cards. ***Disclaimer - I am not in a position to test Doom for myself as of this writing ***
5. Having 1Mb of system memory seems to have *much* more effect on smoothness than aperture size
(esp on Far Cry and KOTOR), so if you see pauses, it might be system memory not aperture that is the
bottleneck.
6. Online benchmarks/articles on AGP settings refer to 32 and 64Mb cards and are probably outdated
7. Increasing the AGP voltage also seems to have an effect on some mobos. It appears that a modern
GFX cards can deal gracefully with the odd bad AGP data packet, although this can also be the cause
of the odd missed frame. Increasing the AGP voltage makes the signal stronger, and can stop
glitching/pausing by removing the probability of bad packets across the AGP bus, especially on an
overclocked system.
S
PS - I really wish this NG maintained a FAQ
))