I have a very similar Tyan board. Almost identical, only difference, mine has upgradeable cache, via coast card.

Tried to build a system around this Tyan board. Everything looks fine until I tried to install a Soundcard. First tried a GUS PnP. Not detected. Oh no, dead? No - runs fine in another board. The Tyan-BIOS doesnt report anything about the GUS. Also tried the Intel ICU, nothing.
OK then I tried the Aztech Waverider 32 as a non Pnp card. Configuration works, but thats all. Also put this card in another baord. Everything OK there.

Tried a ISA NIC and a ISA VGA in the Tyan. Both work fine. Doesnt seem to like soundcards only.

I give up on this, no further idea...

Did you try a PCI sound card?

Did nextstep ever suport dual CPUs? I know there was a x86 version in its final days and its a unix os.
Dsl or custom gentoo install might be a good idea too.

Predator99 wrote:

Tried to build a system around this Tyan board. Everything looks fine until I tried to install a Soundcard. First tried a GUS Pn […]
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Tried to build a system around this Tyan board. Everything looks fine until I tried to install a Soundcard. First tried a GUS PnP. Not detected. Oh no, dead? No - runs fine in another board. The Tyan-BIOS doesnt report anything about the GUS. Also tried the Intel ICU, nothing.
OK then I tried the Aztech Waverider 32 as a non Pnp card. Configuration works, but thats all. Also put this card in another baord. Everything OK there.

Tried a ISA NIC and a ISA VGA in the Tyan. Both work fine. Doesnt seem to like soundcards only.

I give up on this, no further idea...

Now I removed the fixed Dallas to have enough place for a longer card in the bottom ISA-slot and inserted a GUS classic. No drivers or initialization needed. Setup complains about all DMAs I tested, but finally it woks. Playing Duke Nukem with Music and FX.
Strange problem...

Got another Dual Socket 5: ASUS PCI/I P54NP4
Nedd to check if it works...

You are so lucky guy...

Predator99 wrote on 2021-01-08, 11:34:

Got another Dual Socket 5: ASUS PCI/I P54NP4
Nedd to check if it works...

IMG_2956r.jpg

Does that take 2 AT power supplies?

Good point, didnt even notice that...!

Manual is still available from Asus...both connectors are different. As far as I know I have such converter card somewhere and always asked myself what it is used for...

douglar wrote on 2021-01-08, 20:21:

Does that take 2 AT power supplies?

No, one of the connectors is for 3.3 Volts ! Manual attached

That's an interesting setup if you don't have the right style power supply. You just use a pci slot to install your 5 volt to 3.3 volt vrm unit and just backfeed 3.3 volts to the rest of the system.

I don't see any voltage regulators on that board, and P54C wants 3.3V, so that makes sense. It would be interesting to get out the multimeter and find out if those 3.3V connectors go to the CPU, to the PCI or both.

Looking at the manual (the one uploaded by red-ray is slighlty different) its not clear for me if the "5V"-connector is a standard AT one...there is also 12V provided from that.

Or does it have a similar pinout as the 3V-connector? Will check the connections before powering this one on...

Hmm think I have seen a old Dell PSU that had semi standard AT connectors P8 and P9 plus one other P with 3.3v (similar to a ATX Aux power connector).
For use on boards like this and this other one: 3.3V AT power supply connector?

Horun wrote on 2021-01-09, 21:10:

Hmm think I have seen a old Dell PSU that had semi standard AT connectors P8 and P9 plus one other P with 3.3v (similar to a ATX Aux power connector).
For use on boards like this and this other one: 3.3V AT power supply connector?

I have a similar board to the one pictured. http://www.win3x.org/uh19/motherboard/show/6992
The extra power connector has 3xground and 3x3.3v. On my board, the extra connector is only connected to the 3.3V on the PCI slots.
There's an on board voltage regulator near the end of the isa slots that provides 3.3 volts for the CPU.

Looking at that dual socket board, I don't see any voltage regulators, so I image some of those 3.3V lines have to go to the CPU.

douglar wrote on 2021-01-10, 02:05:

I have a similar board to the one pictured. http://www.win3x.org/uh19/motherboard/show/6992 The extra power connector has 3xgro […]
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I have a similar board to the one pictured. http://www.win3x.org/uh19/motherboard/show/6992
The extra power connector has 3xground and 3x3.3v. On my board, the extra connector is only connected to the 3.3V on the PCI slots.
There's an on board voltage regulator near the end of the isa slots that provides 3.3 volts for the CPU.

Looking at that dual socket board, I don't see any voltage regulators, so I image some of those 3.3V lines have to go to the CPU.

Ok makes sense, maybe that Dell PSU was used for a board like yours or the early Soc 4's that have the same 3.3 volt extra connector. The Soc 4 Pentiums (60 and 66) were 5 volt so on the P54NP4 board it probably is same as your board but no 3.3v regulator for the cpu because it did not need it for the cpu.
added: now I wish would have bought that PSU, was at a thrift store but was also about 1/3 larger than standard AT or ATX size and did not think it would fit in any of my older AT cases....

This is the required "POWER CARD 5V to 3.3V" I was referring to. I got this one long time ago and now I am happy I have kept it, never knew what is was used for...

Very nice Tyan board.

It seems that your board FSB is clocked more than 68 MHz.
You have two 166 MMX cpu's right?

Optimal frequency is: 66.667 x 2.5 = 166.7 MHz

When it shows 175 MHz at boot screen, (70 x 2.5 = 175 MHz) ,
you'll need then around the minimum of 68.3 MHz and more at the FSB, then it will automatically round up the cpu clock to 175 MHz.

My super socket 7 board has the same behavior. Setting of jumper @ 66Mhz, the clock is between 67.5 and 68.5 MHz mostly.

That power card looks very well made. That's a sizable chunk of aluminum for the heatsink so it should operate with decent temps too.

Predator99 wrote on 2021-01-10, 08:19:

This is the required "POWER CARD 5V to 3.3V" I was referring to. I got this one long time ago and now I am happy I have kept it, never knew what is was used for...

IMG_3184r.jpg
IMG_3185r.jpg

Interesting - a novelty to me.