Maddmax here is something that may help if you use a Geforce GTS
From overclockers.com
AGP 4x fix on VIA Apollo Pro/133/A chipsets
Author: GShapiro from our forum
I have a Tyan S1854 mobo using a VIA Apollo Pro 133A chipset. Also a Creative Annihilator GeForce2 GTS ULTRA. I have always been able to set AGP4X but it always hung my system when running 3D games. As a result I ran at 2X.
Even though there is no significant difference between 2x and 4x I always wanted to get 4x to work. I paid for 4X so damn it I want it! Now I found a way. It's called the AGP Driving Value. This value is located in the mobo's BIOS for those that use the VIA chipset. With some mobos the BIOS Setup program will have this option. There might also be an option called AGP Driving Control. This can be set to AUTO or MANUAL. Use MANUAL in order to set a value for the AGP Driving Value.
For the Geforce line of cards specifying a value of DA or EA has allowed me to use 4x with no problems! No lockups, no visual artifacting!
The Driving Value can range from 00-FF (these are hex values). If the two I use don't work for you try some other values. If you have a non GeForce card just keep trying different values. Just keep in mind that if you use a 'wrong' value your 3D applications might freeze resulting in having to reboot. Some values will cause terrible visual artifacting.
What if your BIOS Setup doesn't have the AGP Driving Value? There are a couple of BIOS modification programs called WPCREDIT and WPCRSET found at
http://www.h-oda.com. Using these you can modify the BIOS while in Windows. In fact this is what I use.
For my chipset (VIA Apollo Pro 133A) the offset into my BIOS for the Driving Value is X'B1'. Using WPCREDIT you can directly change the default value that is there (this is a great way to test different values to see if they work for you). The values entered with WPCREDIT will disappear when rebooting your machine. However, WPCRSET is designed to startup with Windows and set the value automatically.
I can't speak for any other VIA chipset other then the one I have. It might be that all VIA chipsets have the Driving Value at offset X'B1'. It is up to you to find out.
Here's a link that talks about the AGP Driving Value :
http://arstechnica.com/ask-ars/2000/ask-08212000.html
Here's how to use WPCREDIT and WPCRSET. Keep in mind this article makes no mention of the Driving Value. It does tell you about other values to increase the performance of your VIA chipset as well as how to use the two programs.
http://viahardware.com/memtweakguide1.shtm
Now I know some of you with VIA chipsets can run at 4X without doing what I outlined. However, many people like myself have problems. This procedure is intended for them.
Good luck,
Gary
GShapiro@bigfoot.com
Read more in the thread right here.
*These settings may or may not work with your computer. Please use at your own risk*
*update*Thanks for Hilbert for sending this snip in, again it emphasizes use at your own risk:
"Although the article is correct you might want to reconsider that article or at least make a footnote on it. If anyone sets the signal strength value too low or entirely wrong it can cause a serious problem. Namely the videocard can't boot up anymore since it hasn't enough signal strength .
Thus: the PC boots but the monitor will stay black and there is no way to reverse that situation. Not even clearing the CMOS can fix such a situation.
If such a problem occurs only one solution is at hand, remove the AGP videocard, insert a PCI videocard and connect a monitor to it. That way you will be able to enter the BIOS and reset the AGP values.
If someone not knowledgeable enough he/she can inflict a serious problem. You might want to add this in that article. This is why VIA is not very clear on the AGP Driving Value, and this is exactly the reason.
I was able to verify this problem a few weeks ago.
Feel free to add this text in that article BTW."
<images/home.gif>
<
http://jeeves.flycast.com/gif/57/67/0046757416.gif>
From overclockers.com