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Old 13th May, 2002, 05:17 PM
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spirits247 spirits247 is offline
Join Date: November 2001
Location: UK
Posts: 106

AGP Aperture, the mystery continues............

I'd say I know quite a few things about PC's, but haven't you noticed now and again those grey areas crop up where everyone seems to fling about advice by word of mouth?

And all this advice is constantly conflicting what you've previously read?

Well AGP aperture size is one of those subjects that I just can't get my head around.

You see, I know what AGP aperture size is, I've read all the advice and technical explanations on the internet a thousand times but still can't reach an overall conclusion to grasp this grey area - everyone shouts out something different!

What instigated this thread? Well, I bought a Geforce GTS 64MB DDR to handle a few rounds of online UT. Previously, I had the AGP aperture set to 64MB for my Matrox G200 and this worked well for the GTS. It should, as this size is enough to hold the address space for the onboard video RAM and provide some space for textures if the onboard 64MB is fully utilised.

The thing I don't understand is that when I set AGP aperture to 128MB, UT noticeable accesses the hard drive a lot more and stutters. When I investigated RAM usage, it was A LOT higher with 128MB aperture than 64MB causing higher swap file usage, and this is the problem I can't get my head around.

I was always under the impression that the system would use the video RAM first (in my case 64MB), then switch to using system RAM for textures up to the amount you've specified for the aperture. That's why this setting isn't that important if you have a large amount of video RAM – it’s unlikely it’ll get used anyway.

My experience however, is that this is not the case. System RAM usage goes way up regardless if texture RAM is full or not, because I can't believe UT is maxing out 64MB of onboard memory and filtering that much info into the system RAM. Is something else is going on?????

From my experience, I'd advise people to set the AGP aperture as low as possible without:

a) Hurting benchmark performance
b) Causing game incompatibility

but set it no lower than the memory you have on your card to allow for address space. It seems setting higher apertures just wastes system RAM as it's used regardless if the cards memory is full or not!


Just what is the real deal with AGP aperture sizes?

Do you have to reinstall windows to address the aperture correctly after changing it, because I can't believe the system memory usage between these two settings when I have 64MB onboard video RAM. It appears something is not working right.

Thanks for anyone's advice. I love to clear this grey area up.
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