That struck me as an extremely odd metric to differentiate products by, given its low relevance to non-technical users who don't know what a GPU core even is (except gamers, but they are not buying iMacs). Additionally, most people are going to think adding one more core is hardly worth the price upgrade, and its quite strange to see an odd number of cores.

Apple dont bin them because of price / product differentiation as in Intel / AMD.

Apple bin them only because of yield.

I also think Apple doesn't want to use their M1 as differentiator. They use RAM and Storage instead which is an easier concept to grasp by consumers.

Depends, remember that the 5nm processors overall are fairly new so we have no idea of yields. But if 1/5th of the processors are flawless, 1/5th have one faulty GPU and the rest have more errors (in either CPU or two or more GPU failures) then having twice the amount of CPU's available to sell (at a slightly lower pricepoint) might make perfect sense.

TSMC claimed last year that 5nm yields are better than 7nm.

https://www.anandtech.com/show/16028/better-yield-on-5nm-tha...

It will have a far greater than 1/8th performance impact.

When data structures are power-of-two sizes, having 7 cores instead of 8 could halve performance, since the work gets split into 4 pieces and 3 cores sit idle.

GPU schedulers are much, much more advanced than you give credit.

Well GPU data structures aren’t always a power of two, right? There’s more than textures. For a fact, I know vertex count (vertex shaders?) and screen sizes (fragment shaders?) will rarely be exactly a power of two.

Nope, AFAIK the actual performance impact is < 10 % for most workloads.

Isn't false sharing (as in all your addresses hashing onto the same cache lines) still an issue for power-of-two sizes? You'd have to mess with padding to figure out what's fastest for each chip regardless of core count.