VIA chipset may not be running AGPx4...

For those of you that have a motherboard with a VIA chipset your AGPx4 maybe not working. I was having frame rate issues with complex scenes and while investigating I found that my Abit motherboards AGP bios settings did not actually affect the system performance (particularly the ‘Enable AGPx4’ setting).

Here is a site that explains. I know that this is specific to my motherboard, but a lot of the info is about VIA and my help you.

Good luck…


I have an abit kt7a-raid motherboard. I seem to get reasonable performance with my geforce3 ti500.
I don’t think you’ll notice particularly good improvements in your app unless you use the VERTEX_ARRAY_RANGE extension, which allows you to store your vertices in AGP directly. Getting vertices into AGP memory is time consuming for the driver, but the card getting data from agp memory is faster.
Are you using the VAR extension?

I have an EPOX 8K7A+, an ASUS A7M266, and an A7V266 … all with AMD processors and VIA chipsets. Using GF2 and GF3 I can get close to the 3DMark2001 results of the best game tweakers. I don’t think it’s a VIA or AMD issue you are facing.

Hmm, seems people need reminding that the BIOS option does NOT enable AGP 4X per se! The Via 4-in-1 drivers do that, and you have to tell it TURBO to use 4x.

If you have BIOS set to 4x, and you install the 4-in-1 in standard, then you get 2x.

The point in the post Elixer is the even with the driver and the bios setting AGPx4 wont necessarily work with a GeForce2. If you would have read the article you would have found that there is an Nvidia registry setting that you have to manually edit to enable AGPx4 on VIA.

To all,

I am getting great results now thanks for you concern. I merely posted this message to help out anyone who maybe having a similar problem (no AGPx4).


I wanted to make sure I was running AGP 4x and I am, but the utility reports that fast writes are disabled, so is side band addressing. Does anyone know how to force an Asus A7M motherboard to support fast writes? The utility says it is supported, just disabled. I have turned fast writes on in the Bios, and installed the 4 in 1 drivers in ‘Turbo’ mode.

which video card do you have?

I woudl goto[/url/
and get powerstrip, that is the most accurate program that I know that shows all the crap. I think you can also force features on.
I am not home now, so I can’t test, but
from the last time I dumped the data from my vid card, I have :
AGP aperture - 32 MB
AGP transfer mechanism - DMA
AGP non-local memory - 4.4 MB
AGP driving value - ECh (N-ctrl=14, P-ctrl=12)
AGP revision - 2.00
AGP transfer rates supported - 1x, 2x, 4x
Current AGP transfer rate - 4x
Sideband addressing - hardware support, but currently disabled
Fast write protocol - Enabled
AGP texturing - Enabled

I think this was with Nvidia 21.83 drivers.

John, I have an NVidia GeForce3, I have some very recent version of the XP drivers, I’ll need to verify the version later.

OS is windows 98 release2

Elixer, I’ll try that, thanks for the tip.

[This message has been edited by dorbie (edited 01-30-2002).]

dorbie, I’m not sure. None of the sites I found on the VIA chipset made any reference to this. Sorry.

Make sure that fast writes, AGP4X, and side-band addressing are enabled in the BIOS. Then download and install NVMax, it lets you tweak the GeForce to the hilt …