It will work with any Pentium Pro or Pentium II Overdrive.

Do you have the voltage regulator modules for each CPU? How do you connect a keyboard?
The power inputs look interesting. Do you have the Power supply?

Is the connector on the left edge of the board on the last picture broken? If yes have a look at that so no pins are shorting out.

I saw some UNISYS markings on the parts. Maybe thats a direction...
Based on the dates on the chips i would say its from around 1997.

Some of the chips that look like the bios have lables with "9941" on it ... thats probably the board type

I found this article
https://www.computerwoche.de/a/rechner-fuer-g … pus-vor,1118654

i think it describes the intruduction of the system your mainboard is from...

DerBaum wrote on 2023-10-18, 12:53:

Do you have the voltage regulator modules for each CPU? How do you connect a keyboard? The power inputs look interesting. Do yo […]
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Do you have the voltage regulator modules for each CPU? How do you connect a keyboard?
The power inputs look interesting. Do you have the Power supply?

Is the connector on the left edge of the board on the last picture broken? If yes have a look at that so no pins are shorting out.

I saw some UNISYS markings on the parts. Maybe thats a direction...
Based on the dates on the chips i would say its from around 1997.

Some of the chips that look like the bios have lables with "9941" on it ... thats probably the board type

I don't have a power supply for it, what kind of PSU would it require?

I also don't have VRM modules with it (as far as I can tell, but there is something resembling it, attached are pics of the part, not sure what is that though either).

I don't see anything broken on the board, there is a missing connector for JP4 on the left edge if that's what you pointed out, but I can see it was never soldered to the board, might be something optional / never added to this particular model?

andrean wrote on 2023-10-18, 13:13:

I don't see anything broken on the board...

I marked the port in question. It seems not straight and the plastic is broken in several places.
I thought i saw pins touching each other .

DerBaum wrote on 2023-10-18, 13:30:

I marked the port in question. It seems not straight and the plastic is broken in several places. I thought i saw pins touching […]
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andrean wrote on 2023-10-18, 13:13:

I don't see anything broken on the board...

I marked the port in question. It seems not straight and the plastic is broken in several places.
I thought i saw pins touching each other .
Screenshot 2023-10-18 152802.png

oh you are right, didn't notice that, that is broken indeed, damn!

Are the VRM modules supposed to be connected to the white connectors that stand next to each CPU socket (right besides each socket)? Does anyone know which VRM module should be used for this?

Yes, the 4 white connectors are for the VRM modules.
You need "Pentium Pro VRMs" here, these are somewhat hard to find today. On Ebay there are lots of VRMs for sale, but most are for PIII or proprietary ones.

majestyk wrote on 2023-10-19, 07:58:

Yes, the 4 white connectors are for the VRM modules.
You need "Pentium Pro VRMs" here, these are somewhat hard to find today. On Ebay there are lots of VRMs for sale, but most are for PIII or proprietary ones.

I found this thread: Re: Sourcing a VRM (voltage regulator module) for Pentium Pro motherboard (Micronics W6-LI with 440FX)
where someone mentions using 155681-001 Compaq Voltage Regulator Module , which I can find on ebay even now, https://www.ebay.com/itm/333525573078

do you think this would work for me too? Thanks

Based on the part nos. (38687620) it seems this might be the system board from a Unisys Aquanta QR/6 Server (DM/6 Client)...

https://www.1000bit.it/js/web/viewer.html?fil … f#zoom=page-fit

https://www.tpc.org/results/individual_result … isys.qr6.es.pdf

ECCS (Enterprise Computing & Computer Storage) had a deal with Unisys related to raid sub-systems, fault tolerant and network attached storage so I guess those modules are perhaps interfaces to cards you don't have.

OH BOY!!!

I have several of these. ^.^

That is the "little" brother to the ALR 6x6. Advanced Logic Research. I think they called it the ALR Revolution Quad.

https://linustechtips.com/topic/1088190-first … et-motherboard/

That slot on the very end is broken. it will need to be replaced. It is the slot for the PS/2 ports and other general I/O

Thanks guys, it really does seem to be the board that both of you identified... I have read through the linked docs, forum post, and looked through the youtube videos from that forum, but I still am not sure about the VRM modules, as in, it's nowhere explicitly mentioned which VRM modules can be used with it.

According to this site, the "Compaq 155681-001" is for Pentium III

https://community.hpe.com/t5/proliant-servers … /highlight/true

The vast majority of p-pro voltage regulators are identical. In fact most good pii/piii regulators are even backwards compatible. They just need the same programming pins, and the ability to output 2.8v.

That said, the big difference is the input voltage. Later p3 regulators use the 12v rail as an input. But the ppro ones are exclusively 5v.

https://www.ebay.com/itm/363189522919?mkcid=1 … emis&media=COPY

If you look at the bottom left corner, its often labeled. The linked module should work for ppro

Thanks a lot! I have ordered these VRMs now: https://www.ebay.com/itm/363189522919

I see in the above linked spec documents that a Dual 575W power supply is mentioned at one place. What sort of PSU should I get for this? Can I use a standard ATX with some adapters, or do I really need something else?

hoo boy, thats a loaded question.

it uses standard voltages. nothing special. it conforms mostly to the ATX specifications, afaik. But it is a 100% proprietary power supply.

I've heard of people that cobbled together a DIY solution. You aren't going to need anything overly special, however it is going to require a strong 5v supply. I'll have to pull my own ALR system apart to get a pinout. I dont have any spare power supplies, but I might have a spare power supply CAGE, and that would be a starting place to make a DIY solution. i'll see if I can get to my system this weekend.

andrean wrote on 2023-10-20, 07:19:

Thanks a lot! I have ordered these VRMs now: https://www.ebay.com/itm/363189522919

These VRMs are rated 35W, this might restrict the Pentium Pro models that can be used:

majestyk wrote on 2023-10-22, 06:48:

andrean wrote on 2023-10-20, 07:19:

Thanks a lot! I have ordered these VRMs now: https://www.ebay.com/itm/363189522919

These VRMs are rated 35W, this might restrict the Pentium Pro models that can be used:
ppro_tdp.JPG

oh, hmm, I ordered 4 x 200MHz / 512kb Pentium Pro CPUs, do you think these absolutely cannot work with those VRMs? could it be the case that those VRMs are just declared for a lower power rating, but they in fact could support a bit higher draw (e.g. in this case this 3W difference)?

If it's really a no-go, do you have a recommendation for a VRM that would surely work?

Thanks!

In this case the maximum TDP is just 7% over the nominal rating, so the VRMs will cope with it.
A decent _active_ CPU cooling with the airstream heading toward the CPUs wouldn´t hurt.

majestyk wrote on 2023-10-22, 10:50:

In this case it´s just 7% over the nominal rating, so the VRMs will cope with it.
A decent _active_ CPU cooling with the airstream heading toward the CPUs wouldn´t hurt.

all right, active cooling will be present on all CPUs indeed.

I found this potential alternative: IBM VXI Voltage Regulator Module VRM - FRU 12J2699 VXI P/N: 073 20715 02 REV:B
https://www.ebay.com/itm/223867408142

would these be better?