If you look at the RT cores and SM count, I think they are always equal on RTX GPUs. The problem is, that this doesn't deliver nearly enough performance.
NVIDIA AD102, 2520 MHz, 16384 Cores, 512 TMUs, 176 ROPs, 24576 MB GDDR6X, 1313 MHz, 384 bit
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NVIDIA AD103, 2505 MHz, 9728 Cores, 304 TMUs, 112 ROPs, 16384 MB GDDR6X, 1400 MHz, 256 bit
www.techpowerup.com
Couldn't the architecture have been designed (or optimised for the RTX 4000 series) to double the number, per SM. Or quadruple it? You should be able to turn on RT, without worrying about crippling your framerate, otherwise, it will remain a premium feature, that will keep pushing up the price of the high end/flagship cards.
It can't really be claimed that ray tracing is still a new technology, so I certainly think they could have gone a lot further.
Nvidia could have decided to increase the number of RT cores much more across the whole generation, but they presumably felt that they had such a strong RT advantage already with the RTX 3000 series, that this simply wasn't necessary - that the RTX 4000 series will sell with little effort anyway.
What you got was approx a 52% increase in RT cores, comparing the RTX 3090 TI to the RTX 4090. For the 'RTX 4090 TI', this could be perhaps a 60% increase.
When you look at the design of the RTX 4000 series, it's really just a scaled up Ampere, with significantly improved cooling, built with a new fabrication technology. The production costs have increased, because of the transition to one of the most advanced TSMC nodes (they have certainly made use of the improved transistor density on the top end models).