You've got my attention. Really!
My wish is a P3 (+) motherboard containing not only 2 but 4 slot1 sockets.
Something that's never existed. The Slot-1 FSB, that derives from PPro, can support a maximum of 4 'agents' due to the electrical bus load. But logically it can accomodate 16 cpus. There are Netserver Variants with 2 CPU cards containing 3 PentiumPros each, so it is possible!
I'm also in line with your idea of using VRM modules like the one from necroware. We'd need 4 of these too, makes it easier for testing/debugging/replacing etc as the total CPU power load can get significant.
And I also already checked the slot1 pinout and counted the reserved and unused pins. They should be enoguh to upgrade the slot1 to also support anything above P3, as these need 4 additional signals for the DINV[0:3] signal and for the quadpumped FSB clocking. When someone one day achieves to simulate a 440BX/GX+ chipset into a CPLD or FPGA it's possible to upgrade the slot-1 to support this.
And thats's what I like about slot1: the possibility to built slotkets for all kind of cpus:
It would then be possible to design slotket adapters for Pentium M or Atom or Core2Quad (the last FSB-based CPU).
Imagine 4 slotkets running a Core2Quad each, totalling to 16 cores and running Win11.
My prior thoughts about slot-1 upgrades:
Introduction and CPU Adapter Idea
New Crazy Idea: Build a slot1 pcb for 2 cpus
Being opensource it would permit to design new motherboards in all kinds of formfactor. My utimate dream would be to upgrade my beloved old blueish Gericom 340s8 Webgine laptop from 2003 with a new fitting motherboard that can run Win11. Until then I need to redesign the case for 3D-printing, as the plastic begins to fall apart.
I 'm so crazy for the open-source retro movement, for the fun and ability to learn how it works!
I'll defenitely keep an eye on this thread!