What is Graphics Aperture Size?

[lwh1016]

I have a question. I always see this option in my BIOS to set graphics aperture size but I do not know how to set it for best quality and performance. Setting it from 16MB to 128MB does not really change anything(as far as I felt). And below this setting there is this graphics cache thing that I can set between UC and UWSC. What is the difference between the two and what should I set for best performance? I am using a Geforce FX5200 on AMD Athlon 1.3 Ghz and 256MB 133Mhz SDRAM. Please help!

 

[aceprowler]

Need to give us your Memory size on your video card.

Also, your card is capable of just getting you by on todays games. That is it!

But, AGP Aperture size should be the size of your Video card memory or 64meg - 128meg.

This BIOS feature does two things. It selects the size of the AGP aperture and it determines the size of the GART (Graphics Address Relocation Table).

The aperture is a portion of the PCI memory address range that is dedicated for use as AGP memory address space while the GART is a translation table that translates AGP memory addresses into actual memory addresses which are often fragmented. The GART allows the graphics card to see the memory region available to it as a contiguous piece of memory range.

Host cycles that hit the aperture range are forwarded to the AGP bus without need for translation. The aperture size also determines the maximum amount of system memory that can be allocated to the AGP graphics card for texture storage.

Please note that the AGP aperture is merely address space, not actual physical memory in use. Although it is very common to hear people recommending that the AGP aperture size should be half the size of system memory, that is wrong!

The requirement for AGP memory space shrinks as the graphics card's local memory increases in size. This is because the graphics card will have more local memory to dedicate to texture storage. So, if you upgrade to a graphics card with more memory, you shouldn't be "deceived" into thinking that you will need even more AGP memory! On the contrary, a smaller AGP memory space will be required.

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.

 

[mpjesse]

I've always read that the Graphics Aperture Size should be half that of your total system memory. (I.E., if you have 1GB of RAM, it should be set to 512MB).

Although, I don't think it really matters. I haven't seen a benchmark that shows a significant increase in performance by screwing around w/ this setting.

-mpjesse

 

[lwh1016]

I have 128MB on my FX5200.
Thanks for the very enlightening answer.

Then may I know what is the difference between UC and UWSC?
My friends say UWSC is a newer technology so I should just leave it at UWSC if my BIOS settings allows it. I notice no performance difference with benchmark programs whether I set it to UC or UWSC. I usually leave it on the default 32MB UC.

Thank you again!