Added bonus from that large ground plane - improved signal integrity in the lines directly under it.

This one?
Dual CPU Socket 5/7 Boards

Predator99 wrote on 2021-12-25, 20:02:

This one?
Dual CPU Socket 5/7 Boards

Yes. But it seems many boards didn’t connect the pins to the other slots so the card would only make 3.3v for it’s self

I think I’m just going to end up modifying some board slots

How do I make a 3.3v regulator? I need like a mosfet and a capacitor yes?

Sphere478 wrote on 2021-12-25, 23:23:

How do I make a 3.3v regulator? I need like a mosfet and a capacitor yes?

Depends on the needs. You may be ok with some fixed voltage 1117 LDO regulator to make 3.3v from 5v.
Some caps are needed for sure, LDO might start oscillating without it. The datasheet for the exact regulator you choose will tell recommended values.

Sphere478 wrote:

I’m speechless…
http://dualsocketworld.blog134.fc2.com/blog-entry-158.html

YEAH SCIENCE!

vstrakh wrote on 2021-12-26, 06:48:

Sphere478 wrote on 2021-12-25, 23:23:

How do I make a 3.3v regulator? I need like a mosfet and a capacitor yes?

Depends on the needs. You may be ok with some fixed voltage 1117 LDO regulator to make 3.3v from 5v.
Some caps are needed for sure, LDO might start oscillating without it. The datasheet for the exact regulator you choose will tell recommended values.

https://www.adafruit.com/product/2165

🤔?

I've done this mod in the past to make a graphics card that required 3v3 (chinese Rage XL) work in a 5v only slot. I jumpered a few 3v3 supply pins on the back of the slot, didn't even bother wiring them all. They were NC and not even connected among themselves, and then wired them to a LM2576 switching module set to provide 3v3. (PROTIP: increase the output cap on the module if you do this). Then I did a even worse bodge and stole the 3v3 from the CPU regulator. I was running a K6-2 so the 3v3 was used for the IO only.

Re: PCI Video card works in one PC, not in another

Sphere478 wrote on 2021-12-26, 09:38:

https://www.adafruit.com/product/2165

🤔?

Yeah. This might be enough for some less power-hungry cards (audio/network?), but definitely won't do for video cards.
Switching regulator capable of many amps would be preferable for a "more generic" mod.

Just wire the atx 3v3 directly to the pci 3v3. Maybe add a fuse, either glass ceramic, poly, or electronic.

vstrakh wrote on 2021-12-26, 10:28:

Sphere478 wrote on 2021-12-26, 09:38:

https://www.adafruit.com/product/2165

🤔?

Yeah. This might be enough for some less power-hungry cards (audio/network?), but definitely won't do for video cards.
Switching regulator capable of many amps would be preferable for a "more generic" mod.

There's some super cheap 3A adjustable DC converter modules around, but even that's a bit low for a grunty vid card probably. But there are also some 10A modules that might be worth a shot, but they're not so cheap at the moment.

andrea wrote on 2021-12-26, 09:45:

I've done this mod in the past to make a graphics card that required 3v3 (chinese Rage XL) work in a 5v only slot. I jumpered a few 3v3 supply pins on the back of the slot, didn't even bother wiring them all. They were NC and not even connected among themselves, and then wired them to a LM2576 switching module set to provide 3v3. (PROTIP: increase the output cap on the module if you do this). Then I did a even worse bodge and stole the 3v3 from the CPU regulator. I was running a K6-2 so the 3v3 was used for the IO only.

Re: PCI Video card works in one PC, not in another

Okay this is exactly what I was thinking of doing is taking it from the cpu I/O 🤣

But I would be worried if I ever decided to use a single rail cpu.

Seems like another option would be a male sata connector glued at board edge somewhere

I like the idea of the regulator also though. Could just put it on back of board between 5v and 3.3v pins.

I’m thinking it really only needs to be on one slot because it always seems to be the video cards that need it most of the time

vstrakh wrote on 2021-12-26, 10:28:

Sphere478 wrote on 2021-12-26, 09:38:

https://www.adafruit.com/product/2165

🤔?

Yeah. This might be enough for some less power-hungry cards (audio/network?), but definitely won't do for video cards.
Switching regulator capable of many amps would be preferable for a "more generic" mod.

What’s the most powerful one I could use? Any chance you could send link? Perhaps sketch the schematic I need to make for the power circuit?

What about a high amp diode stack between 5v and. 3.3v pins?

BTW low current, but maybe there's one lying around in junk drawer that regs can be stolen from and/or they're usually in the cheap or free box at yard sales and thrifts... Nokia phone chargers with the barrel plug on put out 3.3-ish... bust them open, there's probably a regulator in there that will run off the 12V or 5V.

edit: check the part numbers, it's possible the current limitation is the tiny transformer, the reg might be good for a whole amp.

Edit2: So another piece of electronic junk you can raid is disused car chargers for old phones or other 5V devices, discarded GPS etc, I've peeked in a few of them and over half seem to have this little sucker in... https://www.onsemi.com/pdf/datasheet/mc34063a-d.pdf so you can fiddle the resistor and cap values and have them put out 3.3 from 5V or 12V

Sphere478 wrote on 2021-12-26, 22:30:

What’s the most powerful one I could use? Any chance you could send link? Perhaps sketch the schematic I need to make for the power circuit?

What about a high amp diode stack between 5v and. 3.3v pins?

Diode would heat up and eventually fail. Hopefully fail open, not short, but that might depend on the diode model.

I'd just look for a prebuilt switching regulator, there are tons of cheap DC-DC converter breakout boards.
Check for LM2596 or MP1584 based, seems the most cheap/common. Those are rated for 3 Amp.
I'd go for unregulated fixed voltage 3.3v ones to avoid risks of possibly getting higher voltages in case of intermittent issues with tuning pots.

I got an idea of how to do this in at least a partially tidy fashion.

1/4” Kaptan tape and 1/8” copper foil tape to add traces to the board.

I’m gonna try it on a p5a first so I can maybe get one slot working for my iRam drive and that on is easy anyway because it has a atx connector for 3.3v

I had a thought,

Might be able to use unused IDE ports as a easy source of power. Looks like there is 5v there. Enough to run 2.5” drives? (I don’t remember) anyway. Possible easy source to grab 5v

But more I think about it it seems like the cards just need a regulator glued to them and some wires soldered to select spots

That or, modify the motherboard it’s self

The regulator should still allow the card to work in 3.3v slots, would just make the 3.3v rail stronger.

I faced the same issue trying to get some PCI(-X) cards running on a socket 7 build I’m currently working on. After manually wiring the 3.3V pins of one slot to the ATX connector I decided to design a small PCB to make my life easier.

With this modification almost any PCI and PCI-X card thrown at my K6XV3+ ran without issues. Even 3.3V only cards after adding the appropriate notch. I have one 3.3V card though which internally connects all PCI supplies, shorting the 3.3V and 5V rails with this setup. So some care has to be taken, or you might at least damage the card (don‘t ask how I know).

I got a few of these PCBs made, not sure if it’s appropriate to advertise these here though. But if someone is interested feel free to get in touch.

Now that is how it's done, bravo

scheiss_freak wrote on 2022-03-07, 21:47:

I faced the same issue trying to get some PCI(-X) cards running on a socket 7 build I’m currently working on. After manually wiring the 3.3V pins of one slot to the ATX connector I decided to design a small PCB to make my life easier.

With this modification almost any PCI and PCI-X card thrown at my K6XV3+ ran without issues. Even 3.3V only cards after adding the appropriate notch. I have one 3.3V card though which internally connects all PCI supplies, shorting the 3.3V and 5V rails with this setup. So some care has to be taken, or you might at least damage the card (don‘t ask how I know).

I got a few of these PCBs made, not sure if it’s appropriate to advertise these here though. But if someone is interested feel free to get in touch.

Oh, that’s perfect!

Mark me down as interested. I’d actually probably be interested in quite a few. Pm me

Seems like I'm not eligible to send PMs yet. But I've set up a simple website to allow for easy ordering: https://recnas.org/

Please let me know if this is inappropriate and I'll remove the link asap.