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View Full Version : Agp Apeture size in megs


Cornmuffen
12-29-04, 06:55 PM
Just curious as to what Apeture size im memory should be used for a 2 gig ram system with 6800 Ultra in XP pro SP2? do gaming don't overclock but get wierd whiting flickering in Half Life 2 since i went to 256.

Dr.Nick
12-29-04, 07:46 PM
I have found 128mb to work the best on my sys. It's best to keep it at 64 or 128, anything higher is overkill.

vläd
12-29-04, 08:45 PM
I would start at 64mb with your system. Then if any probs arise try 128mb to see if it helps. If not then back down to 64mb.

Cornmuffen
12-29-04, 09:09 PM
Does this setting effect in game issues aswell as performance? I have used 128 and 2 gigs of ram and went to 256 according to Corsair saying its good and had half life crash after 10 minutes of play but i decided to go back to 128 and half life runs smooth and no crashes.

I though it was my 6800Ultra but it ran 71c so no overheating and thought it was ASUS probe even shut that off and nothing but how can i confirm this is the agp apeture size effecting ram even though i have 20 gigs of ram equal size and setting.

vläd
12-29-04, 09:50 PM
Basically, the more system RAM and RAM on the vid card, the less you need in the AGP Aperature. Just try the 64mb and see how it goes.

Cornmuffen
12-29-04, 10:51 PM
Can the Agp apeture size effect stability in games if its set higher even with 256 vram and 2 gig system ram?

Sydog
12-30-04, 12:08 AM
Heres me wondering why I had mine at 256mb on my 9600xt (got a 6600gt on Monday). Put the aperture back to 64mb and gained 13fps in HL2 stress test, although some of that could of been from 71.24 drivers, I doubt most of it was.

Dr.Nick
12-30-04, 09:32 AM
Here's a good read about it http://www.rojakpot.com/default.aspx?location=8&var1=0&var2=32

There is more talk on agp aperture, just do a quick search on google for more info. And yes, it can cause stability issues if its set too high or too low.

red_star
12-30-04, 09:59 AM
I have 2GB of ram and my AGP size is 256MB, and I have no problems with it.
Try out 64, 128, 256 and see what the best works for you...

msxyz
12-30-04, 10:08 AM
Back in the old days of the very first AGP systems, people used to say twice the onboard memory amount but never less than 16MB.

Ruined
12-30-04, 10:34 AM
256mb works best for me.

Superfly
12-30-04, 10:41 AM
You guys are all messed up!!! :-)

Its simply your birth weight (8.4 in my case) multiplied by your age = AGP aperture in my case 254 - so I use 256.

nIghtorius
12-30-04, 04:47 PM
You should always set your aperture to the max (even setting it @ 256M when you have 512M)..

golden rule here is:

set it as high as possible as long it doesn't match or exceed your total system memory.

why?

when you use 256M as a aperture size you will lose as much memory when you use 16M as a aperture size. this is because of the AGP table. (which is fixed size for all apertures). I think it was around 8 megs or so.

when you have your aperture set to 256M you have 248 megs reserved for AGP-texturing. storing textures in your main ram when you onboard videomemory can't handle the amount of textures.. meaning if a game has 300MB of textures and you have a 256meg videocard where 16M is reserved for the framebuffers, which is leaving you 240megs of local videotexturememory.. 300 - 240 = 60 megs will be stored into your aperture.. but even when you aperture is set to 256M it will not take 256M but 60+8=68M in this case.

There is no reason to set your aperture to 128M or less when you have 512M or more local memory installed. unless there are some issues / conflicts between systemdrivers concerning the AGP aperture size.

for example: I run 256M agp aperture.. and half-life II won't crash after 10 mins. it keeps of running and running and running.. stutterless.. silkysmooth. @ 1280x1024 4xAA 16xFA.

what happens when you run out of total texturespace?? (VIDEOMEM+AGP_APERTURE)

well.. worst case is that you will see "white" textures in games or games simply crash..

best case is when games are swapping texture data in / out the AGP-aperture and their allocated heap memory.. when a texture is stored on the aperture. the graphiccard can request the texture and the processor will not have a burden of "copying" the texture to the videocard.

games swapping textures in / out the AGP / videomemory will suffer from a extreme performance loss.. cpu utilisation can reach really high in these cases. making demos / games crawl.. becoming unplayable.. even when you have a beast of a videocard installed into your system..

good example: the 6800 NALU demo / Timbury.. THESE NEED 256M of aperture ON A 256M card.

Mud
12-30-04, 05:25 PM
You should always set your aperture to the max (even setting it @ 256M when you have 512M)..

golden rule here is:

set it as high as possible as long it doesn't match or exceed your total system memory.

why?

when you use 256M as a aperture size you will lose as much memory when you use 16M as a aperture size. this is because of the AGP table. (which is fixed size for all apertures). I think it was around 8 megs or so.

when you have your aperture set to 256M you have 248 megs reserved for AGP-texturing. storing textures in your main ram when you onboard videomemory can't handle the amount of textures.. meaning if a game has 300MB of textures and you have a 256meg videocard where 16M is reserved for the framebuffers, which is leaving you 240megs of local videotexturememory.. 300 - 240 = 60 megs will be stored into your aperture.. but even when you aperture is set to 256M it will not take 256M but 60+8=68M in this case.

There is no reason to set your aperture to 128M or less when you have 512M or more local memory installed. unless there are some issues / conflicts between systemdrivers concerning the AGP aperture size.

for example: I run 256M agp aperture.. and half-life II won't crash after 10 mins. it keeps of running and running and running.. stutterless.. silkysmooth. @ 1280x1024 4xAA 16xFA.

what happens when you run out of total texturespace?? (VIDEOMEM+AGP_APERTURE)

well.. worst case is that you will see "white" textures in games or games simply crash..

best case is when games are swapping texture data in / out the AGP-aperture and their allocated heap memory.. when a texture is stored on the aperture. the graphiccard can request the texture and the processor will not have a burden of "copying" the texture to the videocard.

games swapping textures in / out the AGP / videomemory will suffer from a extreme performance loss.. cpu utilisation can reach really high in these cases. making demos / games crawl.. becoming unplayable.. even when you have a beast of a videocard installed into your system..

good example: the 6800 NALU demo / Timbury.. THESE NEED 256M of aperture ON A 256M card.

then explain this:

It is recommended that you keep the AGP aperture around 64MB to 128MB in size, even if your graphics card has a lot of onboard memory. This allows flexibility in the event that you actually need extra memory for texture storage. It will also keep the GART (Graphics Address Relocation Table) within a reasonable size.

not saying you're wrong, just why is keeping the GART size down unimportant (at least compared to texture memory from your reckoning)?

nIghtorius
12-30-04, 06:27 PM
then explain this:

It is recommended that you keep the AGP aperture around 64MB to 128MB in size, even if your graphics card has a lot of onboard memory. This allows flexibility in the event that you actually need extra memory for texture storage. It will also keep the GART (Graphics Address Relocation Table) within a reasonable size.

not saying you're wrong, just why is keeping the GART size down unimportant (at least compared to texture memory from your reckoning)?

the increase in the GART table from 128M to 256M is neglectable. The article you quoted were just a bit "reserved" in this setting. He also actually recommending a huge aperture even when you have lots of videomemory.

Times change. Is the same article will be written again in this time period he would probably recommend setting it to 256M also.

--- informational stuff..

Interesting read about DIME/AGP/Aperture (http://www.faculty.iu-bremen.de/birk/lectures/PC101-2003/09graphics/PC101/feat_05.htm)


In AGP systems, the texture is stored only once. It is loaded onto to the system memory (RAM). From here, due to DIME, it is used by the graphics card. This has many advantages. By this method, the texture is stored only once. The video card has access to more amounts of memory. Also, when the memory is not needed for graphics, it can be used by the system for other purposes. The frame buffer remains in the graphics card, as this is a special and faster type of RAM (Video RAM). For smaller operations, the graphics card uses the system RAM.


This is done through a device called Graphics Address Remapping Table (GART). The Operating System allocates discontinuous memory to the AGP in 4K sizes in the main memory instead of one big chunk of memory. However, graphics cards require large portions of continuous memory. Therefore, the Operating system allocates an amount of continuous memory on top of the main memory. The graphics card accesses this block as though it were main memory. The GART then remaps these virtual addresses into physical addresses in the main memory. Hence, it appears as a large chunk of memory to the graphics card.

http://www.faculty.iu-bremen.de/birk/lectures/PC101-2003/09graphics/PC101/Images/img_feat05c.jpg

Mud
12-30-04, 06:37 PM
nice substantiation thanks :)

Cornmuffen
12-30-04, 09:50 PM
Good Information, I see that raising the size can effect stability even when running more than a gig of ram too.

im running everything fine at 128 so and no lag with eye candy up high.

cheers folks

$n][pErMan
01-11-05, 02:21 PM
If you have a 256mb Card ... its kind of trivial. Ive used 64... 128.. and 256 and noticed no difference in FPS, benchmarks, or performance. I say use 64mb if you have no problems.