The package is a BGA, containing a multi chip module. There are 4 dies, each 9mm x 9mm, spaced out by 5mm. The core voltage and frequency vary according to the cooling available to the chip. The chip contains a temperature sensor on die, and increases or decreases the operating voltage and frequency to maintain a target operating temperature at the die. The allows the maximum possible performance to be achieved, given the cooling that is available. In a colder environment the chip will operate at a slightly higher voltage and frequency, and return a higher hash rate than in a warm environment. Simulation runs show that the best silicon will have a TDP of 250W when operating at the name plate (nominal) 400GH/s. Worst case silicon will consume a few % more power to reach this nominal 400GH/s. Note - simulation results can be out by +/- 20%, although they typically come in high (expect lower numbers in real silicon).