RTX 2080 Ti - 50% faster than RX 5700 XT at 4K, mainly due to VRAM buffer limit on RX 5700 XT.
Navi 21 has 80 CUs, 256 bit memory bus, 2.2 GHz clock speeds, at the very least
2.2 GHz is 16% above what RX 5700 XT clocked. And RDNA2 GPU are supposed to have higher IPC, than RDNA1.
Solely on CU counts, and VRAM size buffer, Navi 21 should achieve 100% performance above RX 5700 XT.
And that is excluding IPC and clock speed differences.
And yet, AMD demoed a GPU that is 70% faster at 4K than RX 5700 XT.
Something does not add up.
A little follow up.
If RDNA2 achieved 10% IPC increase - 80 RDNA2 CUs at 1.8 GHz will perform just like 88 RDNA1 CUs clocked at 1.8 GHz.
2.2 GHz clock speeds are 16% above RX 5700 XT clock speeds(1887 MHz).
In essence, if AMD has found a way, that 256 bit memory bus is enough for 80 RDNA2 CUs that GPU should be, with full config, with 2.2 GHz around 135% above RX 5700 XT.
Around 10-15% above RTX 3090. In 4K.
And this is only with 10% IPC increase.
This is all theoretical calculation.
So we better pray, that 256 bit bus is enough to feed those CUs, and that AMD was able to find a way, that those CUs scale in performance, similarly to RDNA1 architecture.