A Compac F with multiple BM1397 would not be that great, considering USB isn't good for more than about 15 watts and one BM1397 will handle that on its own. When doing a multi-chip setup, one also has to consider that the surface of the IC is copper-plated and electrically grounded, so you can't share heatsinks across multiple chips unless they're at the same ground potential. BM1391 doesn't have that limitation, but as you say, they're also not as fast. BM1387 can clock down to around 60W/TH (but very low speeds, ~50GH per chip at best), 1391 around 45W/TH, 1397 around 35W/TH.
Hey sidehack, thanks for chiming in, big fan here! You're right about the USB power; I was thinking if I'll design a miner myself, maybe to use barrel jack connectors to give additional power to a USB-stick-based miner, since I saw laptops with dual 200W or so PSUs connected via barrel afaik (those gaming kind of laptops with desktop processors).
Don't tell anybody, but I'm working on BM1391 next. Supposed to have some M30 chips inbound to play with too but so far I have no info on how to use them. I (GekkoScience) tend to not publish a lot of info either because I got it under NDA or because the manufacture and sale of my miners is the primary income for multiple households and I don't want to risk undercutting my own business or the employees that rely on it.
Oh nice, interesting to hear your plans with new chips and insights! Quite sick that you even get NDA access at all, didn't expect it. And I totally get that you don't want to give away plans and undermine your own business. I hope I won't cause your business any harm by publishing the info that I will be able to find and reverse engineer.
In my mind, I just want to publish footprints and KiCad component files in a way (by license) that is for educational and open source purposes and will lead to development of open source home ASICs. It would mean people could e.g. have them made in small runs for them and their family & friends, even when more well-known products like yours from GekkoScience or from Futurebit are sold out or unavailable in the region for example
Also this project shall aid in the freedom and independence aspect of Bitcoin - theoretically, with just having to source chips and plans available, one could even produce PCBs locally or at home and solder components themselves (not that it would make sense to do but just the idea that you don't have to rely on overseas PCB manufacturers, transport, customs etc. to get a miner in your hands sounds quite cool to me).