Mar 02, 2021 · The R4 Antminer is a costeffective and powerful Bitcoin miner. One of the key features is that the R4 possesses a unique fan that does away with excessive noise. Rating: Shark Extreme 2 (8 GPU) The Shark Extreme 2 rig is an eight GPU card miner that is a popular choice for GPUbased mining setups. It can miner a great number of different ...