> Assume FP64 units are ~2-4x bigger.
From the top of my head, overhead is around 10% or so.
> Why would gamers want to pay for any features they don't use?
Apparently FP80, which is even wider than FP64, is beneficial for pathfinding algorithms in games.
Pathfinding for hundredths of units is a task worth putting on GPU.
https://en.wikipedia.org/wiki/Motorola_88000 (under "Registers": "32 80-bit (88110 only)")
https://en.wikipedia.org/wiki/Extended_precision (see section titled "IEEE 754 extended-precision formats")
From the top of my head, overhead is around 10% or so.
https://www.youtube.com/watch?v=lEBQveBCtKYApparently FP80, which is even wider than FP64, is beneficial for pathfinding algorithms in games.
Pathfinding for hundredths of units is a task worth putting on GPU.