3090’s is never good for mining or gaming . The msrp is way 2 high for hashing
For gaming that 10% performance is not worth the price difference with the 3080’s .
I think 3090 is better for mining in all aspects except price. But now, when 3080 availability is zero and prices are very high, 3090 is rather attractive even in price sense. Here we have 3090 for 2k$ and 3080 for ... 2k$

Well i’m comparing mrsp prices . I can easily make a 6 gpu rig with scalper 3080’s at 1700-1800 cad but thats pointless . In a month or 2 stocks will be replenished and more miners will come online . Diff will go up .
Buying a 3080 at 300-400$ premium will set back ur roi by 2 much .
Then factor in EIP 1559 , you’d barely turn in a profit by the time eth 2.0 rolls out (if out in 2023) .