Excelsior wrote on 2022-10-01, 13:27:

Hello, […]
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Hello,

I have a DEC Alpha motherboard - I don't know the exact model and I don't have or found any manual.
It's a socket 499 processor board with mixed DEC and Intel chipsets.
The only problem is that I can't find the Power Switch connector so I don't know where to connect the 2 pin power switch cable on the motherboard.
The motherboard mentions the Reset, SPK, Fan, HDD connectors but no Power Switch connector is ever mentioned.
However it has 2 possible suspects: the 2 pin connector (it's written HALT above it) and a 5 pin ACT connector but I am not sure if any of these is the one I am searching.
I tried it with a known working PSU but nothing happens.
Do you know where I can find a manual or at least which one is the Power Switch connector?
Thanks in advance!

Someone posted this http://www.zx.net.nz/mirror/h18000.www1.hp.co … ital/index.html link here recently on another thread, maybe you can find something helpful over there.

Also seems the board can be found on the retro web https://theretroweb.com/motherboards/s/dec-al … i-164#downloads

though no mention of a power switch jumper.

You could try to short the ATX powerup pin directly... Though I would first try to verify if the mainboard actually uses the ATX pinout.

edit: sadly, the usermanual on the retrowebpage is for another digital mainboard.