AGP performance control

[LeChimp]

Anyone know what the BIOS setting "AGP performance control" does?

 

[Mem]

What does AGP driving control do and how should I set it?

By selecting a manual hex range (00h-FFh) we are setting the timing of the signal that your video card's driver uses to communicate across the AGP bus

Default for the AGP Driving control is going to be 'Auto'. This is pretty much akin to your 'auto' ram-timing selection; it is the lowest-common denominator settings that are going to yield you the widest compatibility at the cost of performance.

'Manual' AGP Driving Control setting is VIA's way of skirting chipset design and driver issues, by allowing them to configure for optimal scenarios.

"Since the 'AGP Driving Control' BIOS option is specific to the VIA
chipset's AGP implementation and there are multiple motherboards based
on the VIA chipset, I would have to say that for certain motherboards
there is no magic setting that works with every graphics card and
motherboard combination. For instance, a setting of CCh on a particular
motherboard is not going to mysteriously work better with every card
than a setting of BAh."

As for how to find out the specific settings recommended for various video cards, the best recommendation would be to contact your video card vendor first (and I would attempt to contact the chipset provider as well, if they are an IHV (like nVidia)). Ask them what their recommended manual timing is.

The only straight answer on manual timings that I have been able to get is from Epox and Tyan. For the original Geforce 256's, they recommend A8h for timing control. This is independent of driver, but dependant on chipset. With the Geforce 256 GTS they recommend a manual setting of BAh. Asus, keeping with PC tradition of doing your own thing, recommends a setting of B9h for their 6600 Pure card. Tyan used to recommend DCh with everything (as a few other vendors have posted on their websites), but with all Tyan VIA-chipset motherboard BIOS updates posted after 2/15/2000, you will notice they now recommend CCh."

Best to leave it on auto setting,

Note modifying this setting changes the signal timing to the graphics card. If you get it wrong, the graphics card won't boot, and you'll be left with a black screen. The only way to remedy this is to temporarily use an old PCI graphics card, change the driving control setting, and then reboot.

 

[LeChimp]

I think this is something different, it can only be enabled or disabled.
I'm using an A7V333.

 

[r0tt3n1]

Specific to VIA chipset motherboards, this setting lets you manually set a `timing` range for your video card to communicate thru the AGP bus with. Depending on which video card, manufacturer, video chipset, model etc.. you can manually specify a hex range for it to use. The `AUTO` selection should do fine for most things. But if you happen to have an older GeForce 256, you may need to select A8h for proper performance. If things are working fine, leave it alone.

 

[LeChimp]

But there is no AUTO or ah8 settings.
Just enabled or disabled.