Today we will begin to address some of the more common questions from the bit coin talk forum.
Question: “Can you clarify that the nominal wattage of the chip itself is ~250W and the wattage of the system at the wall is ~350W? Both numbers have been used but it isn’t exactly clear what they represent.”
Answer: At the nominal operating point (400Gh/s) the best silicon will consume ~250W according to our simulations. There is some variation in silicon however, so some silicon will consume a few % more or less. This power level is at the chip only.
The system has 2 power conversion stages between the wall plug and the chip – first an ATX power supply that outputs 12V. This supply is about 88% efficient. Then there is a second supply stage on the module board the chip is mounted on. This second supply stage converts the 12V down to approximately 0.7-0.8V that the chip runs at. The combination of the losses in both PSU stages and the additional consumption from the pump, fans, controller, etc. account for the difference between the 250W at the chip and about 350W at the wall.