Calcul de l'AGP Aperture Size

C'est sur le site lostcircuits.com, tous les secrets révélés, du BIOS etc.

Donc pour l'AGP, en anglais dans le texte:

Je cite " Total system memory / (video memory [MB] /2)

Ci-dessous l'article complet :

AGP Aperture size

The amount of main memory that is allocated for direct memory access (DMA) of the advanced graphics port or DiME (direct memory execution). The hypothetical advantage of the AGP design is that the graphics engine can use the main memory as part of a unified memory architecture (UMA). In this case, the graphics adapter can access textures directly from the main memory (DMA) and, more importantly, process the data directly from and to the main memory, bypassing the on-board graphics memory. This feature requires a certain amount of system memory to be allocated for graphics operations. Too little will result in poor graphics performance, too much will fill up the system memory and take up space required for other operations.

With the increase of on-board graphics memory (currently up to 128 MB on the video card itself) this option has lost its relevance. Were the original recommendations to set the AGP aperture to about � of the total system memory, a good approximation now would be:

Total system memory / (video memory [MB] /2)

* In other words, if you are running 128 MB system memory and have a 4 MB video card, the optimal AGP aperture would be:
128 MB / (4/2) = 64 MB
* For a 8 MB video card, the equation would be:
128 MB / (8/2) = 32 MB
* and for a 64 MB video card:
128 MB (64/2) = 4 MB

Please note that this is only an approximation to explain the principle. In real life situation, the AGP aperture should be kept at a minimum of 16 MB. Most modern games will require a minimum of 64 MB texture space in the system memory and with upcoming games like Doom3 and UT2003, there will be even greater demand on system memory reserved as texture buffer (AGP aperture)

AGP-4X mode / AGP-8X mode

Depending on the graphics adapter used, this setting should be enabled to use the advantage of the AGP x 4 transfer protocol. Some graphics cards are still not capable of taking advantage of AGP 4X, examples are the Kyro2-based AGP adapters while the latest cards are capable of using AGP 8X for a transfer rate of 2.48 GB/sec. It will be awhile until we see the benefit of AGP 8x but it will come.

One additional benefit of AGP 8x is that it allows to place two separate AGP ports on the mainboard. Up to AGP 4X, the system architecture only allowed a single AGP interface which forced many users of multi-monitor solutions to resolve to PCI-based secondary and tertiary graphics adapters. "


Source : www.lostcircuits.com

David.