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Which AGP Chipset has the widest range of compatibility?

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First post, by douglar

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I've read over this webpage: https://www.playtool.com/pages/agpcompat/agp.html

Reviewed the chart:

The attachment AGP.png is no longer available

Seems clear that an universal AGP Motherboard would have the best compatibility.

I have a universal board. https://theretroweb.com/motherboards/s/asus-a7v333 It seems to be electrically compatible with 3.3v cards.

I'm a little more worried about valuable late AGP cards. Manual says it supports up to AGP 4x. If there any to check to make sure it won't roast AGP 8x cards?

Manual also says:

CAUTION! To avoid damaging your AGP/AGP Pro graphics card, your computer's power supply should be unplugged before inserting your graphics card into the slot.

What is the reason for that?

And then there are BIOS issues. Some early VGA cards like https://theretroweb.com/expansioncards/s/his-4r2ch2s1 don't seem to initialize properly. The computer boots, but no VGA signal is generated. Are the BIOS issues going to be a hit-or-miss situation or is there some way to judge BIOS compatibility other than "stick it in and see if it works?"

Reply 1 of 4, by swaaye

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I've been using a KT333 board (ECS K7VTA3 v6) for many years as my fastest board that can run 3.3v cards. It works fine with AGP 8x cards too. Some KT333 boards don't support 3.3v though. There are different revisions.

VIA's AGP was not exactly perfect. There are compatibility issues with some cards. Radeon 8500 needed some BIOS updates back in the day for example for VIA boards.

Unplugging the power is always a good idea if you are going to add or remove hardware. An ATX motherboard is otherwise always powered to some degree. You don't want to accidentally trigger it to fully power on while hardware is halfway seated.

Reply 2 of 4, by The Serpent Rider

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Intel i815 or SIS 645DX.

I must be some kind of standard: the anonymous gangbanger of the 21st century.

Reply 3 of 4, by douglar

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So let's see-- Here's my research results on the three chipsets--

  • Intel i815 --> Probably the most compatible chipset but limited to a PIII-S 1.4 GHz Tualatin with the "B" stepping and 1.0Ghz Coppermine with the "A" stepping
  • SIS 645DX --> Supports P4 Northwood 3.06 GHz CPUs and has good AGP compatibility but only supports single channel memory, which can cause 5% to 30% performance drop from the best case
  • KT333 --> Supports an Athlon XP 2800+ Thunderbird or a Athlon XP 3000+ Barton which are likely the fastest here, but comes with the usual suite of Via AGP & PCI compatibility quirks

Does that look pretty accurate?

Reply 4 of 4, by Repo Man11

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douglar wrote on Today, 18:28:
So let's see-- Here's my research results on the three chipsets-- […]
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So let's see-- Here's my research results on the three chipsets--

  • Intel i815 --> Probably the most compatible chipset but limited to a PIII-S 1.4 GHz Tualatin with the "B" stepping and 1.0Ghz Coppermine with the "A" stepping
  • SIS 645DX --> Supports P4 Northwood 3.06 GHz CPUs and has good AGP compatibility but only supports single channel memory, which can cause 5% to 30% performance drop from the best case
  • KT333 --> Supports an Athlon XP 2800+ Thunderbird or a Athlon XP 3000+ Barton which are likely the fastest here, but comes with the usual suite of Via AGP & PCI compatibility quirks

Does that look pretty accurate?

There's a thread dedicated to this, it's worth a look. Socket 423/478 Motherboards with Universal AGP Slot

A lot of times when you first start out on a project you think, This is never going to be finished. But then it is, and you think, Wow, it wasn't even worth it. - Jack Handey

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