Trick a Pentium 3 motherboard without GPU installed to post (Via Apollo, PCI) \ VOGONS

Trick a Pentium 3 motherboard without GPU installed to post (Via Apollo, PCI)

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First post, by Nicolas 2000

Posted on 2025-12-10, 08:47

Nicolas 2000 Offline

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I have an application that runs a headless Pentium 3 on a motherboard with Via Apollo chipset. In the original design, a motherboard with onboard GPU is used but no monitor connected. These motherboards are very hard to find, the variants without onboard GPU are far more common. But in this application there is no room to add a graphics card. Even with a 90° PCI bracket there is no room.

Is there a way to trick these motherboards into thinking there is a graphics card installed or otherwise get them to post? Something in the bios, or shorting two PCI pins or something...I'm just guessing.

Assume a motherboard like a ATX GIGABYTE GA-6VX7-4X but anything similar is valid.

Reply 1 of 6, by marxveix

Posted on 2025-12-10, 10:02

marxveix Offline

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There are PCI-E riser cables, maybe there are AGP and PCI versions as well. If there are, add some cheap PCI graphics,
can be low profile and low power, these take max 4w. https://theretroweb.com/expansioncards/s/ati- … -xl-pci-8mb-sdr

There are plenty integrated vga motherboards with Socket 370 / Slot1, intel 810/815, also ati, sis and via.

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Reply 2 of 6, by myne

Posted on 2025-12-10, 10:36

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Some bioses have options to halt on "no errors". Might allow no video. Might not.

Presumably you can confirm via lan

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Reply 3 of 6, by Nicolas 2000

Posted on 2025-12-10, 10:47

Nicolas 2000 Offline

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I hadn't even thought about how to make a test setup for this beyond listening for a POST-beep. 😀

PCI riser cables exist, but are so hard to google because of PCI-E riser cables. I have found one but it is very short. No added value over my 90° riser.

But anyway, any info on how exactly a motherboard determines whether or not a GPU card is installed? Perhaps something that could be mimicked with a tiny Arduino spewing out whatever signals or messages are expected?

Reply 4 of 6, by myne

Posted on 2025-12-10, 10:51

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https://www.dmp.com.tw/app/webcamera/vga.htm

Ignore whatever the hell they're doing, and that card, or something like it might be the way.
8bit, baby

Reply 5 of 6, by Nicolas 2000

Posted on 2025-12-10, 10:55

Nicolas 2000 Offline

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According to ChatGPT, the motherboard checks for a GPU are so thorough that you can basically only spoof it by building a GPU...so I'd either need to have a BIOS that goes full nihilist when selecting "halt on no errors", or a way to get the GPU installed at some distance from the motherboard.

Still according to ChatGPT, halt on no errors still halts on no GPU in most BIOSes. There are some exotic ones that have a setting to ignore no video. But I assume those would be found in mobo's from minni PC's, not big desktops.

Last edited by Nicolas 2000 on 2025-12-10, 11:01. Edited 2 times in total.

Reply 6 of 6, by Nicolas 2000

Posted on 2025-12-10, 10:57

Nicolas 2000 Offline

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myne wrote on 2025-12-10, 10:51:

https://www.dmp.com.tw/app/webcamera/vga.htm

Ignore whatever the hell they're doing, and that card, or something like it might be the way.
8bit, baby

That is the cutest VGA card ever seen. It might even be low enough to fit directly. Not sure I still have an ISA slot in the particular mobo I'm having here. I had a rather small Rage GPU laying around already, PCI. But this one is smaller by the looks of it.

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