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AGP on Asus P5A-B issues

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First post, by jroman

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I have an Asus P5A-B rev 1.04 with the latest Beta BIOS that I'm trying to get working with any of the AGP 3.3V compatible cards that I have (Voodoo3 2000, Riva TNT2, GeForce 3 Ti 200). It works fine with PCI cards. I'm running at the suggested FSB for whatever CPU I've been using (K6-2 350, Pentium MMX 233, K6-3+ 450).

I have read that the Ali chipset in this is particularly flaky with these specific GPUs. After getting the bad VGA BIOS beep code a few times, I swapped to a PCI card and disabled a few BIOS settings and got the Voodoo 3 working. I then turned off and unplugged the machine to add a USB expansion card and when plugged back in it won't boot. My first guess would be that the CMOS battery was dead and it forgot the changes I made but I put a new one in last week. And also clearly turning it off worked fine before when I swapped to the Voodoo in the first place.

Before I went through the whole process of changing the cards around again, does anyone have suggestions for how I might approach this?

Reply 1 of 9, by bloodem

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I have two of these boards: one is rev. 1.03, the other is rev. 1.04. I’ve never had any issues with any of the AGP cards I’ve tried (and I’ve certainly never encountered a card with which the board fails to POST).
Are you sure the board is otherwise OK, no damaged traces or anything like that? What you are describing seems to point towards a hardware issue.

2 x PLCC-68 / 4 x PGA132 / 5 x Skt 3 / 1 x Skt 4 / 9 x Skt 7 / 12 x SS7 / 1 x Skt 8 / 14 x Slot 1 / 6 x Slot A
5 x Skt 370 / 8 x Skt A / 2 x Skt 478 / 2 x Skt 754 / 3 x Skt 939 / 7 x LGA775 / 1 x LGA1155
Current PC: Ryzen 7 9800X3D
Backup: Ryzen 7 5800X3D

Reply 2 of 9, by jroman

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There's nothing obviously out of sorts on the board physically. And it doesn't seem to have other issues besides the AGP flakiness. The fact that it started working after I change the one BIOS settings could be a fluke, but if it were bad hardware I think I'd expect it to be more erratic.

The only thing I can think of that's weird about the configuration is that I can't set VIO to 3.3V which is what the K6s want. There's no jumper setting for it. So it's on 3.5V. I don't know how that would result in this specific malfunction but that's it as far as weirdness.

I am using the original AT power supply with it (the board is in the original ASUS branded Compact Baby AT case) so I could imagine that being a factor if just the 3D was failing or something.

Reply 3 of 9, by Imperious

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The 3.5v setting is not for the CPU VIO, it's for the AGP/DIMM/Chipset voltage. I would at least have a look at the power supply and see if any bulged caps?
Maybe set the bios to defaults and see if that makes any difference. Some of the AGP settings in the bios can cause issues with some hardware combinations,
especially on these early AGP boards.

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PC's from XT 8088, 486, Pentium MMX, K6, Athlon, P3, P4, 775, to current Ryzen 5600x.

Reply 4 of 9, by jroman

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I think I solved it. It is a hardware issue, but not in a way you might expect. Some combination of the motherboard standoffs being too short and the case itself being a little warped meant that expansion boards apparently aren't seating correctly. I never thought to try the board outside the case because I was using the AT power supply that's part of the case. Didn't think the hardware problem would be with the one non-electrical component in the build.

Reply 5 of 9, by Imperious

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Good find. I've come across this with my AT case as well. Sometimes it's the card itself and can be problems with the bracket that screws to the rear of the case.

Atari 2600, TI994a, Vic20, c64, ZX Spectrum 128, Amstrad CPC464, Atari 65XE, Commodore Plus/4, Amiga 500
PC's from XT 8088, 486, Pentium MMX, K6, Athlon, P3, P4, 775, to current Ryzen 5600x.

Reply 6 of 9, by bloodem

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jroman wrote on 2025-04-23, 02:52:

I think I solved it. It is a hardware issue, but not in a way you might expect. Some combination of the motherboard standoffs being too short and the case itself being a little warped meant that expansion boards apparently aren't seating correctly. I never thought to try the board outside the case because I was using the AT power supply that's part of the case. Didn't think the hardware problem would be with the one non-electrical component in the build.

Ah, OK! You did not mention that the motherboard was in a case. This is always the very first thing I try when facing issues - remove the board and test it on an open bench. 😀

2 x PLCC-68 / 4 x PGA132 / 5 x Skt 3 / 1 x Skt 4 / 9 x Skt 7 / 12 x SS7 / 1 x Skt 8 / 14 x Slot 1 / 6 x Slot A
5 x Skt 370 / 8 x Skt A / 2 x Skt 478 / 2 x Skt 754 / 3 x Skt 939 / 7 x LGA775 / 1 x LGA1155
Current PC: Ryzen 7 9800X3D
Backup: Ryzen 7 5800X3D

Reply 7 of 9, by jroman

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Now that it's up and running I went through the process of installing the Ali AGP driver and tweaking some BIOS settings to try to get the best performance. I'm getting around 2000-2100 in the default 3dMark99 which I believe is low for what this hardware should get. It's hard to tell without a central database but I see a lot of folks reporting scores closer to 2500. In the course of playing with the settings, I had a couple runs where 3dMark99 instead gave me closer to 3000 (after a reboot). The CPU score also jumped from 5300 to 6800. I can't make this happen consistently, although I first saw it jump that high when I set the RAM timing to 2T in the BIOS. That seems way too high, although obviously if that's possible with this hardware that would be great. Anyone have thoughts on a) what the right score should be for this hardware combination and b) why I might be getting such wildly different results? Also if anyone has suggestions for the best benchmark to just check CPU performance to make sure nothing weird is happening there that would be appreciated.

Reply 8 of 9, by bertrammatrix

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jroman wrote on 2025-04-27, 23:17:

Now that it's up and running I went through the process of installing the Ali AGP driver and tweaking some BIOS settings to try to get the best performance. I'm getting around 2000-2100 in the default 3dMark99 which I believe is low for what this hardware should get. It's hard to tell without a central database but I see a lot of folks reporting scores closer to 2500. In the course of playing with the settings, I had a couple runs where 3dMark99 instead gave me closer to 3000 (after a reboot). The CPU score also jumped from 5300 to 6800. I can't make this happen consistently, although I first saw it jump that high when I set the RAM timing to 2T in the BIOS. That seems way too high, although obviously if that's possible with this hardware that would be great. Anyone have thoughts on a) what the right score should be for this hardware combination and b) why I might be getting such wildly different results? Also if anyone has suggestions for the best benchmark to just check CPU performance to make sure nothing weird is happening there that would be appreciated.

2T would make a noticable difference if you can pull it off. My personal favorite test for memory settings is a quick windows installation on a spare drive. Early in the process it extracts some files and is VERY prone to halting if there is any instability. I find this even more reliable then just running the timings which may "seem fine" but lead to problems later.

Also, I don't know anyone who doesn't overclock a ss7 setup like that...you really want the FSB as high as you can get it.

Reply 9 of 9, by zuldan

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jroman wrote on 2025-04-27, 23:17:

Now that it's up and running I went through the process of installing the Ali AGP driver and tweaking some BIOS settings to try to get the best performance. I'm getting around 2000-2100 in the default 3dMark99 which I believe is low for what this hardware should get. It's hard to tell without a central database but I see a lot of folks reporting scores closer to 2500. In the course of playing with the settings, I had a couple runs where 3dMark99 instead gave me closer to 3000 (after a reboot). The CPU score also jumped from 5300 to 6800. I can't make this happen consistently, although I first saw it jump that high when I set the RAM timing to 2T in the BIOS. That seems way too high, although obviously if that's possible with this hardware that would be great. Anyone have thoughts on a) what the right score should be for this hardware combination and b) why I might be getting such wildly different results? Also if anyone has suggestions for the best benchmark to just check CPU performance to make sure nothing weird is happening there that would be appreciated.

On a K6-2+ 550 I get 3600+ in 3dMark99 with a Voodoo 3000.

A couple of things...

- Chipset driver MUST be install prior to the VGA driver (I use 2.13 https://theretroweb.com/drivers/118)
- The ALi AGP Control Center must be used to change some default AGP settings

The attachment agp_utility140.zip is no longer available

Use these settings

The attachment ALi AGP Settings.png is no longer available

So maybe try something like this and then run 3dMark99 again;

1. Uninstall your VGA driver
2. Install the chipset driver
3. Install the VGA driver
4. Run ALi AGP CC