Antminer S21 Series — AustraliaThe S21 is Bitmain’s current flagship Bitcoin mining generation and the range most Australian buyers should be looking at first. It represents a substantial efficiency jump over the S19 series, which is the single factor that most determines whether a machine stays profitable under Australian electricity prices.The S21 variants explainedThe family splits along two axes: silicon tier and cooling method. The base S21 and S21 Pro are air-cooled and the most straightforward to deploy. The S21+ is a mid-generation refresh with improved efficiency. S21 XP models use higher-binned chips for the best J/TH figures in the range. Hyd variants are hydro-cooled, delivering far higher hashrate per unit and much lower noise at the cost of requiring a cooling loop. Imm variants are built for immersion tanks.Which one suits your setupFor a home or small-scale Australian installation, an air-cooled S21 or S21 Pro is usually the right call — no supporting infrastructure, straightforward setup, and a manageable single-circuit power draw once you have the right wiring in place. If you are running multiple units, or installing anywhere that gets genuinely hot, the hydro models earn their extra complexity quickly. Immersion variants only make sense as part of a purpose-built commercial deployment.Power planningS21-class machines draw roughly 3,500W and above. That is well beyond a standard Australian 10A power point, so a dedicated circuit installed by a licensed electrician is mandatory rather than optional. Multiple units will typically need three-phase supply. Confirm your switchboard capacity before ordering.