by brianolson 5 hours ago
Yield. Some fraction of cores had a speck of dust or something, but at 38/40 good cores per chip they got economical yield
And then even if some nodes had 40/40 "good" cores, it would make load balancing a lot more complicated if core counts vary. Easier to turn them off at the hardware level.
Couldn't some chips have 40 good cores, while others have only 36? Do they all need to be exactly 38?