As far as i understood the board works with 10 or 20 chips. Not with any other number. There are 2 groups of 10 chips each. Thats why both boards are nearly the same price i guess. A bitburner x is only a bitburner xx with 1 instead both 10-chip routes enabled.
You know this for a fact? Yes the chips are logically organised in chains, but initial discussions were quite clear there would be two boards. Hence why I say, check with the man himself.
I have sent burnin a PM seeking clarification. I bought 10 chips (all I could afford a the time) with the understanding there would be a 10 and 20 chip version. There's been no mention of the X version for some time now so I'm getting concerned, hence why I've asked a few times if the plans are still going ahead.