Cooler Master makes decent power supplies, but I'd recommend either Corsair or Seasonic PSUs. What types of graphics card(s) are you using? I would definitely get a power supply with more than 526W, or whatever their calculator is recommending. There's no harm in having "too much" power, as the watt rating is only an indication of what the power supply CAN deliver if needed, rather than a measure of constant power use. Efficiency relates to how much of the PSU's power is lost to heat as opposed to being used to power your computer. You'll want an "80 Plus"-rated power supply. There are four different levels of 80 Plus ratings: Gold, Silver, Bronze, and just "rated," with Gold being the most efficient. My personal recommendation is to get one of the Corsair TX V2 series power supplies (also called their Enthusiast Series), either the 750W or 850W unit depending on your configuration. Their AX (or Professional Series) units are even better, though they're pricier.