Do you consider the AMD CPU Ryzen 7 5800X3D hashrate of 17.75 kH/s as listed on nicehash.com to be fake?
I don't have a chance to check because I think CPU mining is pointless at the moment. And one processor needs a lot of hardware.
It is 100% fake. Bigger cache doesn't give it any advantage in RandomX because 5800X already has enough cache (2 MB per thread), so both will run at 10-11 kh/s with tuned memory.