Dumb luck in succeeding with Void Linux Box Build using proprietary pita HPG3705 Micro Tower MB
 

I was searching ebay for a cheapo new am4 motherboard for a linux based econobuild desktop and came across an oem motherboard for a HP G3 705 Micro Tower. It is based on the B350 chipset and recently (11/20/2020)got a bios update to support all ryzen am4 processors up to Zen2 generation. It was only $42 new , and I had a coupon! So I impulsively "bought it now". As anyone in the know about HP proprietary crap knows, this was an ill conceived plan and unlikely to end well.
However, it did end well!

When I received the mobo, I inspected it and found the thing suffered from two terrifying oddities. Firstly, it had three 6 pin connectors (one was the dread P2 connector) instead of the standard 24pin connector for the PSU. Secondly, my extra am4 wraith cooler did not fit the mounting hole pattern on the mobo.
The second problem was solved first and easily. It was an intel mounting hole pattern on the B350 AMD mobo( I guess they needed a cheap lower height cooler for their case and this was their solution). So I got an openbox thermaltake 95 watt rated intel hsf at microcenter for $15. Problem solved.

The first problem led to a lot of googling and reading, and what I read was all bad. This oem board was only meant to work with one particular 280W psu and it was almost unobtanium and the few available were rapaciously overpriced. But, there was a business in selling adapter cables to use standard aftermarket ATX psu's with this class of HP (and Dell) oem mobo.
I am saved, right?
Wrong!
My particular model is not on any of the list of supported devices for these cables. My model is not directly referenced in a forum documenting an attempt to use any of these cables. And there are several variations in wiring for these cables for different models, and references in the forums to smoking toasted mobos for some people who used the incorrect cable.
So, I stupidly throw good money after bad and gamble on the cheapest of these cables at the most cited vendor for them (moddiy.com). It was an HP Z230 motherboard adapter cable on sale for $9.99.
I get the cable, hook everything up and there is still one frigging 6 pin power port on the mobo that I can't plug into (labeled sata power)!
I fire it up anyway connecting my ssd to sata port 1 (figuring if any of them work, that would be the one).

It just worked! I installed void linux & updated bios, no problem. I kind of wish the one incident of undeserved incredibly good luck in my life related to a power ball ticket in stead of this, but I'll take it.

And, its a nice mobo. Four ram slots, B350 chipset, whats not to like (see firstly and secondly above - heh,heh,heh ...)?
YMMV. The cable theysent me doesn't look like the picture on the vendor website. So, if you try this yourself, do not expect with confidence that your motherboard will not burn. If anyone is interested, I can post a photo of the magic cable. I am doubtful anyone is interested, it was a dumb idea, but possibly a funny story to share.