AGP Aperture Size - Does it really matter?

[antdude]

http://www.athlonmb.com/ubbhtml/Forum5/HTML/000053.html

Is this still true for Matrox G400 32 MB cards (I have a non-MAX model)?

[jws]

hmm, interesting thing happened to me. I did a reset of my bios in "optimal" mode. I went to play games and found I locked up a couple of times in Rune. This hadn't happened before, so I went to my bios and found my AGP size was 64. I had previously set it to 256, so I set it back. I played several more hours without lockups again. I can't say it wasn't just coincidence, but I think I'll stay at 256.

[xortam]

This isn't a gaming thread so I hope it gets relocated where others can find some of this useful information. I liked the BIOS site that the athlonmb thread referred to: the memory timings explanation was especially good.

[Brian R.]

There are some computers which will not boot with a G400 unless the AGP aperture is set to 256 MB. Some Dells fall into this category.

Dead - Dead - Deadsky

[Kruzin]

Like xortam, I think this is more a Matrox Hardware issue, rather than a games specific issue. This thread is relocated to Matrox Hardware

And Brian is correct. Some systems won't even boot with a G400 if the aperture is not cranked up to 128 or 256...

[Brian R.]

I think Matrox recommends 256 MB in general

[Gurm]

Ok, I'll run through this again.

The correct AGP aperture setting is... well... whatever you want it to be. I would personally never pick an aperture size larger than half of my main system memory.

However, on perhaps 50% of the motherboards out there (and maybe more), the AGP aperture size option in the BIOS is thoroughly broken. These machines will require you to set your aperture size to 256 in order to obtain the correct functionality of your video card.

If your motherboard is working properly, you can set the AGP aperture to anything you like, including 0.

However, more and more games won't run correctly unless you have the aperture at a reasonable size. Which is why I recommend half your system RAM.

Now all of this is moot if you have a newer board, as the new VIA chipsets and the 815 from Intel only allow a maximum of 128MB of aperture. Pity, since I'd have liked to play with the 256MB that is half of my RAM.

- Gurm

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Listen up, you primitive screwheads! See this? This is my BOOMSTICK! Etc. etc.

[ayoub_ibrahim]

hmm, thought 64 MB was the AGP limit for 815 motherboards!

[Wulfman]

my system does not boot the first time I switch it on - only the long "beeeeeep" (graca not found..)..

switch off, switch on - everything is allright..

mobo: epox 8kta

mfg
wulfman

[Pertti]

Originally posted by Gurm:

However, on perhaps 50% of the motherboards out there (and maybe more), the AGP aperture size option in the BIOS is thoroughly broken

Care to explain that one Gurm ?

[Wombat]

Wulfman,
It sounds like you aren't getting power to all of your devices. How much stuff is in there? What kind of PS?

[Ovi]

Originally posted by Gurm:

However, on perhaps 50% of the motherboards out there (and maybe more), the AGP aperture size option in the BIOS is thoroughly broken. These machines will require you to set your aperture size to 256 in order to obtain the correct functionality of your video card.

[/B]

Gurm: By this 'broken implementation', are you referring to the fact that the texture memory (non local) that is available is usually less that half of the AGP aperture setting?
Cheers
Ovi

[dZeus]

no, that's the correct implementation. If you would get the amount of memory availble that is the same as AGP aperture size, then the implementation would be incorrect. Aperture size is never mentioned as being 100% the same as non-local memory availble for video textures.

[Ovi]

Thanks for the info, dZeus
Cheers
Ovi

[Gurm]

What I mean by "broken" is not an empirical "this function call is broken" but more a general "not right" sort of thing.

Hrm. That came out poorly. Basically, if you have a 32-meg card, and you turn off the AGP aperture, all games should run. Right? I mean, they run on a 16-meg PCI card, so why not on a 32-meg AGP card with no aperture?

But, on literally 50% of motherboards in production (recent boards excepted), turning off the AGP aperture will cause crashes clear across the board, no matter what card you are using. It's not just a Matrox thing.

In addition, there is NO reason for ever turning the AGP aperture up to twice or even 4 times your system RAM, which is what happens if you have 64 megs of system RAM and an aperture of 256MB.

It is a well documented phenomenon. It tends to be traced to the motherboard manufacturers and NOT the video card companies. If you run a search of the archives you'll turn up a lot on this.

I've always lucked out and had boards in my own personal machine that correctly implemented the aperture settings. But I've seen lots of boards that don't.

*shrug*

- Gurm

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Listen up, you primitive screwheads! See this? This is my BOOMSTICK! Etc. etc.