Is that with four chips?
Yes (can't be otherwise). 133GH/chip, if every chip requires $150-250 in VRMs alone it's out of the market already.
What happens if you put them in power chain? 13 chips should feed nicely from 12V PSU - I calculated 1877A of current @ 0.87V - can they handle this?
That's a lot of Amps. Is that the reason why it isn't being done? (or is it feasible?).