Overall, our chip most closely resembles a modern "hot CPU" design (Intel Sandy Bridge E, AMD FX-9, SPARC T4, etc.). The package is a BGA, 45mm x 45mm external dimensions. The total die area is approximately 324mm^2. The die is split in 4 - i.e. under the metal lid there are 4 dies in a square arrangement, each approx 9mm x 9mm with 5mm gap in between each one (for better heat dissipation and spreading).
Thanks for the update and I am glad you confirmed this detail. The entire package is 45mm by 45mm, is the lid smaller? If so can you provide the lid dimensions?
If lid occupies entire chip size that would be a surface area of 20.25 cm and a heat flux of 12.3 W/cm^2.
For those wondering what I mean. Two example chip packages, pretend each is 45mm x 45mm. The surface area of the lid for the chip on the right is significantly larger.
One highly relevant feature regarding power use is that the GN chip incorporates on-die temperature sensors and a control system designed to adjust voltage and clock speed to the capacity of the cooling system. Thus if the cooling system can dissipate a greater amount of heat, the software can "overclock" the chip to fit it's power usage to the heat dissipation capacity, and produce greater hashing capacity.
Similarly, the chip will "underclock" itself in response to external circumstances that reduce the available heat dissipation capacity (say, a very hot day, a failure in the cooling system, a blocked air vent...). The overall design intent is for the chip to always operate at the maximum possible hashrate dictated by the circumstances.
Good to hear. What is the operating temp the software targets? 60C?
Finally, one recent piece of news is that we have received results for the stage-III thermal test (full physical prototype) from our cooling system partner.
Glad to hear that. Care to share any details on radiator size? Will all fittings be PC water cooling standard (G/14 threads, 3/8 or 1/2 ID barbs/compression fittings) to make upgrading radiator and other components possible with off the shelf components.
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. 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.
Thank you. So I see it something like this.
Chip power: 250W (~333A @ 0.75VDC)
Board power: 284W (~24A @ 12VDC)
System DC power: 315W (~@27@ 12VDC 284W board + 31W for controller, fans, pump, etc)
System AC power: 350W (~3A @ 120VAC assumes 90% ATX PSU efficiency)
The module board is ~4" wide and approx 10" long (may end up a little longer, up to 12" - we are still configuring the power connectors). Here is a draft layout - note this is not final and is subject to change. Dimensions in mm.
Thanks. Eyeballing the diagram I assume the case is 2U high. That would make the fans 80mm. If diagram is to scale that puts the FET heat sinks @ ~60mm (+/-10%). Are FET heatsinks removable (out of warranty of course). The heat flux should be < 1 W/cm^2 which is trivial in immersion cooling. The "shorter" the board height the closer they can be spaced and the less very expensive Fluorinert I need to buy.
Also some users may wish to replace them with water blocks.
Note - this design is not final, and is subject to change.
Of course and understood.
Yes - we plan to add complete module boards to our website shortly. These can be directly controlled via either a serial port, or USB. We will be open sourcing the drivers in CGMiner.
Excellent. Thank you for all the info/details. Keep it coming.
