I do not know.

possibly.

If all the pins are routed to the other slots.

.

Why the need?
3.3v cards that require that voltage normally shouldn't fit into 5v pci slots, there's a notch preventing insertion.
Universal pci cards shouldn't care what's the voltages there.

Shouldn't, but a lot of later network, USB and IDE/SATA cards still fail to work in 5V-only PCI 2.1 slots.

My feeling is that it's likely to be N/C at each slot... so then if you're gonna string jumper wires slot to slot hooking up all the NCs, then you may as well have a regulator supplying them without taking up a slot. For a single card, no solder to board, you might get away with a regulator like those -5V mods, and just tucking three thin wires into the slot at the appropriate pins.

Atheatos added a wire to a PCI video card that needed 3.3 which his Asus P5A lacked to allow it to work in that motherboard. https://youtu.be/U8W6A-VKroE?t=418

vstrakh wrote on 2021-12-12, 14:41:

Why the need?
3.3v cards that require that voltage normally shouldn't fit into 5v pci slots, there's a notch preventing insertion.
Universal pci cards shouldn't care what's the voltages there.

The notch only indicates signalling voltage. Some later PCI cards apparently require +3.3Vcc present on the slot to work properly even with 5V signalling.

vstrakh wrote on 2021-12-12, 14:41:

Why the need?
3.3v cards that require that voltage normally shouldn't fit into 5v pci slots, there's a notch preventing insertion.
Universal pci cards shouldn't care what's the voltages there.

I have a bunch of dual notch cards that I’m pretty sure aren’t working because of lack of 3.3v

Repo Man11 wrote on 2021-12-12, 16:07:

Atheatos added a wire to a PCI video card that needed 3.3 which his Asus P5A lacked to allow it to work in that motherboard. https://youtu.be/U8W6A-VKroE?t=418

I saw that, it’s what got me thinking

I saw that, it’s what got me thinking

He said in the video that required pins are not connected to anything. So only direct soldering is possible (slot or card).

You could use bodge wires on the back of the board to connect all the +3.3Vcc pins and use a selfmade card with a DC-DC converter to supply +3.3V to the slot.
But you could also put the converter behind the mobo and connect it to the wires directly.
Maybe add a few capacitors for decoupling on the back too.

Doornkaat wrote on 2021-12-13, 05:52:

You could use bodge wires on the back of the board to connect all the +3.3Vcc pins and use a selfmade card with a DC-DC converter to supply +3.3V to the slot.
But you could also put the converter behind the mobo and connect it to the wires directly.
Maybe add a few capacitors for decoupling on the back too.

Not a bad idea.

Has anyone done this? We need a guide and BOM

Full BOM:

Junkbox scrapings.

BitWrangler wrote on 2021-12-12, 15:26:

My feeling is that it's likely to be N/C at each slot...

I can confirm this. I've probed the pins A21,A27,A53 on all PCI connectors on my 5v-only Socket-7 motherboard.
There are no connectivity whatsoever, not between the slots, not between the 3v3 pins within the same connector.

There are more pins designated for 3v3 power (not just those 3 tested), but I didn't bother checking every single one, it's obvious there's no point.

Doornkaat wrote on 2021-12-13, 05:52:

You could use bodge wires on the back of the board to connect all the +3.3Vcc pins and use a selfmade card with a DC-DC converter to supply +3.3V to the slot.
But you could also put the converter behind the mobo and connect it to the wires directly.
Maybe add a few capacitors for decoupling on the back too.

With an ATX board you don't even need the DC-DC converter, just hook up +3.3V from the ATX. Just 10 ugly bodge wires on the back.

Hacky simple version for no 3.3V supply.... get a bridge rectifier, snip off the inputs and put the negative output to 5V and positive output to 3.3V pin. That gives you two diodes in series dropping 1.4V from the 5V line, pretty close if your 5V is running at 4.8, not so great if it's running at 5.5V.. use with caution.

The atx to nc pins method seems like a good option.

What wire should I get?

Someone have a old mobo layin around they wanna test this on? 🤔

I got to thinking, it’s usually just the lowest pci slot that needs it because that’s where I usually put the video card and it seems most video cards that you can buy these days need the 3.3v so if I just make one 3.3v pci slot that might be enough. As for power, I could just run it to a sata connector or the atx plug if it has one, otherwise a regulator from the AT connector would seem to be in order

I have quite a few half height cards that would be nice to use, shame no one has made a interposer…

That would be a easy no solder option!

I believe a thin gauge solid core jumper wire would hold and make contact when pushed into the PCI slot beside the pin on top through the little hole to the side.

I’m speechless…

http://dualsocketworld.blog134.fc2.com/blog-entry-158.html

Looks like japanese to me. 🤣