GP102 471 mm²
TU106 445 mm²
Even with RT and other extra cores/features not being used the Turing chips run power limited all the time, Pascal had a similar issue with power limits on the higher end chips. Locked low voltages, locked low power limits, the Nvidia way of keeping cards cool and efficient. Where as AMD goes and blasts the voltages high, power limits high to try and catch up in performance to the neutered NV cards. Sad but true.
Don't even wanna know how much power TU106 would eat if all features are used fully at once, the thing would go thermonuclear. To get just regular old graphics power unlimited on TU106 it needs around 300W :/ But all cards are stuck with 200-250W max OC. TU106 ideally needs a power limit similar to GP102 but oh no that Nvidia can't allow as people would OC the crap out of their cards, GPU makers would need to use better VRM and even better cooling then they already do Turing cards.
Ray tracing is usable but available software? Limited. Performance? Pretty poor.
They could have invested the die space into regular old graphics hardware but the cards would be power monsters especially when power limits would be high or not present. Most higher performance Nvidia GPUs and even AMD are power limited quite a bit as otherwise they go completely nuts, pushing power astronomical for small performance gains.
GTX Turing... they will keep it all below TU106 level of performance for sure.