View Full Version : AGP-2x, how to do it?

Hermann Assbeck
12th March 2000, 07:27

i have a matrox mga-200 8MB sdram, chaintech 5agm2, and an amd k6-2 400Mhz. How can i activate the agp-2x-option? All progs i have tested, tells me, i only have agp-1x. The reg-hacks didnt works.

Can anybody help me?

Hermann Assbeck

12th March 2000, 09:21
If it's running in 1x, there is a reason for it. On bootup, the Matrox drivers run an AGP test, where it writes to AGP memory, then reads it back. If it does not read the same as it wrote, it drops to 1x. This is an indication of bus noise. You can try to force it with the registry hacks, but that will often lead to instability.

Since you tried the hack, and it did nothing, it is most likely because your registry has more than one video card entry. Edit the registry hack. You will see the exact location of that entry in the registry. Open regedit, and look at that location. The hack applies itself to ...\display\0000\... If there is more than the \0000\ (0001, 0002, 0003) it indicates more than one video card in your registry. Either clean up the registry, or edit the hack to reflect the correct location.

Of course, after going through all of this (assuming your sys will even run 2x without locking up), you will see no difference. 1x, 2x, or 4x means very little in reality today...

Hermann Assbeck
12th March 2000, 09:53
I have tried the hacks, but after booting windows 98 the system hangs, i cant do anything. My system is not overvlocked, are there any other solutions?

Hermann Assbeck

Hermann Assbeck
12th March 2000, 10:04
What kind of test is the agp-test? Is it possible to run it manually to find out what's going wrong there?

Hermann Assbeck

12th March 2000, 11:15
I think the test is run in hardware, so there is a way for you to run it.

The two reasons I'm familiar with for a videoboard to default to AGP 1x are an overclocked front side bus and "motherboard noise." Since we've eliminated the first possibility, the latter is probably true.

If you are otherwise happy with your motherboard, I wouldn't worry about it. The effects of AGP 2x are negligible at best in games at resolutions you would find "playable." As I understand it, AGP 2x comes into play when the size of textures exceed the capacity of your board's RAM.


Hermann Assbeck
12th March 2000, 14:40
What do you mean with "motherboard noise"

Hermann Assbeck

12th March 2000, 15:30
"motherboard noise" is just the interference between the wires and components. That's probably a 6-layer motherboard (most VIA/ALI SS7 boards are), and so it has a lot of noise. If AGP 2x hangs your computer, you probably can't pull it off.
It's nothing to worry about anyway. You don't even use the potential AGP 1x has to offer, and don't need 2x. This is especially true of the Matrox cards. They use a different form of AGP transfer than most other cards, and it's almost as fast as the other form of AGP, running at 2x.

Don't worry about it any more.

Hermann Assbeck
13th March 2000, 01:25
Tanks for this information.

Hermann Assbeck

14th March 2000, 00:26
Wombat, what is the "different" method of AGP you mentioned Matrox uses? I haven't heard about this before.


System Specs:
Athlon 600
WD AC180000 UDMA/66
Creative 48mx
Atapi Zip 100
Microsoft Internet Keyboard PRO USB
Microsoft Intellimouse w/Intellieye USB
No ISA, no floppy

[This message has been edited by rogman (edited 14 March 2000).]

14th March 2000, 00:59
Almost all cards today use DMA mode AGP. It will copy the texture to system ram, then copy it back to video ram when needed.

Matrox employs DiME mode. This will copy the texture to system ram, then execute directly from there, without taking the time to copy it back to video ram.

Eliminating that extra transfer results in very efficient use of the AGP bus. Something Matrox does well, and why 1x on a Matrox card is almost as efficient as 2x on any other card...

14th March 2000, 04:28
It might sound a dumb proposal, but did you enable AGP 2x in your bios settings ? (as far as I followed, in the thread nobody mentioned this).

14th March 2000, 04:54
... and do you have a divider for the FSB/AGP ratio ?

I suppose you're running an FSB of 100MHz and as long as you have set your divider to 1/1, you're AGP bus will also run at 100MHz which is 50% above specs (66.6MHz).

Have a look into your manual ynd figure out if there's an option to change that divider to 2/3.

14th March 2000, 10:10
try changing the agpfallback in registry to 1, this did it for me

agpfallback = 0 means no test run set to 1x in default

agpfallback = 1 means run the test if it pass set to 2x if not 1x

if setting agpfallback = 1 still gives you 1 x then use the registry hack provided in this site to force 2x

hope this help

Hermann Assbeck
14th March 2000, 15:31

o.k., i will try to answer each of you.

In the bios agp2x is enabled (i have checked it 3 times ;-))

Right, the fsb is clocked at 100Mhz. The agp is clocked at 66Mhz, theres no jumper to select another speed. The board do this automaticly. 100Mhz FSB = 66 Mhz AGP.

agpfallback, this term i have seen in the registry, but i had no idea what it means. I will try it, and then i will post the result here.

Thanks again for your help.

Hermann Assbeck

P.S. Excuse my bad english, german is my home-language.

Hermann Assbeck
14th March 2000, 15:34

in the registry the entry agpfallback is set to "0". I will try it.

Hermann Assbeck

Hermann Assbeck
14th March 2000, 17:33

i have changed the entry agpfallback to "1", but after the restart it goes back to "0", and the agp runs at 1x. ;-( I have tested this 4 times, the same result...

Any ideas?

Hermann Assbeck

14th March 2000, 17:44
Yea, I have an idea.

Leave it alone.

You have already stated that if you force 2x that the "system hangs".
This is the sign that your system is too noisy for 2x.

You could jump through the hoops of replacing RAM, Mobo, hard drives, etc. until it is quiet enough for 2x. Then you would see that there is no practical difference. Your benchmarks would remain the same, your games would run the same.

You are beating your head against a brick wall for no real gain. Accept that 1x is what you need to run at for your system to be stable, and that it does not really matter. You are not alone. A large number of people have to run at 1x. It simply doesn't matter.

Hermann Assbeck
15th March 2000, 17:46

Hermann Assbeck