Thanks Alberto, then I have to sell the key to the miner who bids the highest.
Whats the best way for me to prove that I have the key, without disclosing the private key and public key to a miner ?
There is no safe way to do that, even signature text messages include the public key.
And those are running on some zero-point module free energy?

Here nobody mention the electric cost of those cards, but yes, you need to include it to your budget and it will be a lot.