AGP Aperature size - what does it do?

Zal

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Up until now i have ignored the bios setting for AGP aperature size, until i was told (by an unreliable source) that the AGP aperature size int he bios settings (in MB) dictates how much memory is sent to the gfx card per second. My default was 64mb, but i have a 256mb ati radeon 9800XT. I was just wondering how raising the agp aperature size would effect my systems performance, or if it even makes any difference atall?

i guess the real question is, what is the AGP aperature, and what does it do?

Thanks for your help :)
 

TheRod

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FALSE, AGP aperture size don't affect GPU performance. You can set it to 64, 128 or 256 if you want, but you will not see any difference in performance.

You can read this :
<A HREF="http://www.ocfaq.com/article.php/overclocking/vidcard/43" target="_new">http://www.ocfaq.com/article.php/overclocking/vidcard/43</A>

I personnaly always set it to 128Megs.

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CorpusBiscuit

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I've read that the AGP should be set to one half (1/2) the MB of the vid card. So for a 256MB vid card, set the AGP to 128. Why? I have no idea, its just what I've read, so maybe someone more knowlegable can confirm or refute this.
 
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He mentions disagreeing with the half the memory size. Really it depends on what you plan on doing with the card. I have played with the size on my system with limited results and Lars here, and the boyz at FiringSquad have both posted reviews with a few setting showing minimal but 'traceable' differences. But really it won't make much difference as long as it's not TOO small.


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Terracide

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Wich game uses more than 128-256MB GFX-RAM? :)
For it's only then, and ONLY then that AGP-Aperature comes into play :)
When there is NO more FREE RAM left on the GFX-card :)

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coolsquirtle

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okay let's see if i remember what crashman said correctly

Back when i was ur age (LOLZ) Graphic cards have like 4 mb of ram onboard, alot of time u can run out of ram. AGP Aperature size acts as "extra" ram for the graphic cards to use. Nowadays most cards have more than enough ram to run so AGP aperature dont matter much anymore. In the instrution manual for the MSI 875P mobo i have, it says to set the AGP aperature size half of ur video card :D

I hope i get the concept right

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Terracide

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I have an GF4 Ti4600 128 MB and an Aperature size of 0 MB, and never had any problems? :)

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coolsquirtle

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i never said u would have problems = ="

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Crashman

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That's absolutely wrong, but it's been repeated so much it sounds right. That's what happens when somebody makes something up, the rumor spreads, and when it's widespread enough people assume it's fact.

The truth is, I've tested all sorts of cards with all sorts of memory, from 16MB to 256MB and everything in between, and found that the best setting was 128MB for Aperture.

Even on systems that only had 128MB of RAM, 128MB AGP Aperture seems to work the best.

The only application where I could find a significant performance difference was 3D Mark 2001, which would allow you to perform more tests with increased aperture.

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coolsquirtle

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ya Crash, but on most mobo motherboard manual, they recommand setting it to half ur Vram.

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Crashman

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Nay, it was mostly a 3D-Mark 2001 thing where the program was looking for additional RAM to cache textures, the 64Mb texture test was looking for greater than 64MB AGP Aperture, the best setting was 128MB. There are probably some obscure games out there that do the same thing, hence I recommend everybody set their AGP aperture to 128MB.

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Crashman

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That makes ABSOLUTELY NO SENCE, because the LESS Video RAM you have, the MORE reliant your system is on AGP Aperture! For example, the 64MB setting is not enough to run the high test on a 32MB card under 3D-Mark 2001. You need 128MB to run it. But you probably DON'T use AGP Aperture AT ALL in the same test if you have 128MB of Video RAM.

I've heard 1/2 of SYSTEM RAM before, which makes some sense because they don't want you sharing too much RAM, but 1/2 of Video RAM is ludicrous, and directly opposite of what you REALLY need!

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Terracide

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This sounds odd for me as the speed of the AGP-port is WAY below the speed of the onboard GFX-RAM controller?
But does anybody have a link to any test that can show this, as I have heard these claims before, but never seen any proff, that it should be true? :)
(not saying you're a lair though :) )

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Zal

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Thanks for all your help, that does make a lot of sense. I also thought that an onboard card would be faster than its AGP equivalent... i have yetr to test this theory, as onboard graphics adapters are always quite far behind the upper clas agp cards (Eg, at the moment most onboard gfx adapters, apart for laptops, dont go higher than the geforce 4 series... but i may be wrong), whereas the bare moinimum most ppl opt for their desktops is a 128mb radeon 9600 pro for £50.

I set my AGP aperature size to 256mb, and did not really notice any difference in performance in games :/
 

Crashman

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You'll believe it if you hear it from a review writer? Fine, I'm a review writer, the application where I noticed this was 3D-Mark 2001, and 128MB was the best setting, regardless of other hardware.

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Crashman

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BTW, I'm not talking about video RAM, or substituting video RAM for AGP aperture, what I'm saying is that certain applications require a certain amount of RAM to do things like cache textures and AGP Aperture is that additional buffer. Which is why I'm saying having MORE AGP Aperture should be MORE helpfull to cards that have less RAM. But that doesn't take away from the fact that it's better to have more RAM on the card.

You can't "put more RAM on the card" you already own, haven't been able to for years. So your only choice when you need a larger buffer is to assign more AGP aperture.

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coolsquirtle

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:S stupid mobo makers :D

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Crashman

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It's probably a problem of software writers and hardware designers not communicating properly. As for me, I have to go by observation. It works in fact, but does it work in theory? LOL.

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Terracide

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I didn't say that, I said I just would like to see some test-results confirming this :)
Seeing is beliving ;)

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Crashman

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I no longer have enough cards on hand to do a comprehensive review. But if you guys would like to send me some older cards, say, a GeForce2 GTS, Radeon DDR, GeForce3 500, and Radeon 8500, I'll be happy to set it up!

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Terracide

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Why older cards?
Because they have limited gfx-RAM?
Just post the findings you already have, and I look at it? :)

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Crashman

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I no longer have the "findings I already have" because it's been a couple years since I did the tests. But if you look in the Graphics Card Archives exhaustively you might find them!

Yes, because they have limitted RAM.

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Terracide

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Crashman:
Do if you own a gfx-card with 128-256MB RAM this dosn't affect you? :)
Or have I misunderstood you? :)
No flaming inteded here, just curious, born that way ;) *L*

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Crashman

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You caught me! Damn. I quit testing various aperture settings BEFORE I got a 128MB card!

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