Yes we are using LGA1366/LGA2011 type mountings. Basically any heatsink with 80x80mm hole pitch will fit. But be careful with top side, since our A1 chips are spread out to a bigger area than basic 40mm x 40mm OR 45mm x 45mm contact area. However we include a heatspreader on topside, so if you plan to use your own water cooling, it should fit without modification. BUT please make sure with us before you do this.

The rear side has a solder pad, intended as cooling contact for heatsink. We use immersion plating to achieve better planarity on the pads -> better heat transfer.

Cooling is needed for both sides. So far in one of our stress tests we reached 46-47Cdeg (measured at top-side heatsink & A1 contact point) when we were running 250-254GH/s per card speeds. This temperature was reached by having fans at 100%. I guess we could reduce the fan speeds a bit to get better W/GHs^-1 numbers and reduce sound levels.


- Noncetech

I don't know if someone has already mentioned this, but we found out that engineering chips can be undervolted by first starting up at 0.85V, then when chips are hashing adjust output voltage. This would require that your DC/DC feedback is designed to allow dynamic voltage adjustment without making too much under-/overshoots.


- Noncetech

The heatsink+fan combo seen on the picture is about 0.22W/Cdeg heatsink fan combo, which is cooling the topside of A1 chips. We have another bigger 0.16W/Cdeg heatsink+fan cooling the board. We measured some temperatures today at 800MHz and it was quite stable at 65-67Cdeg and for another board 55-58Cdeg. Our FETs and inductors stablized around 60Cdeg.

We had two board stack-up configuration. I guess the another board is not getting fresh air enough. We may need to adjust the upper heatsink alignment, so that its pushing the air out properly.

We have 8 chips under those heatsinks.

EDIT: We don't have proper equipment for accurate on-board current measurements at this moment, thus unable to measure our buck's efficiency at different loads. But we had a wattage meter. I don't have numbers now for 25GH/s setting, but we were getting around 490-510W in total at ~490GH/s (16 chips configuration). Raspberry and ATX PSU were drawing 25W, so it needs to be reduced from total amount in order to get board specific. All the chips did overclock quite nicely. Still need to determine the optimum spot.



- Noncetech

Here is our initial testing results (2x4 IC configuration @ 0.85V):



Just ran for short period of time. And here is snapshot from our build:




- Noncetech

Hello, could some HW guy give small guidance on the following topics:

- RESETN, CLOCK and CLKMUX are also 1.8V, right?

- When I have multiple chip design, and I have square wave clock generator -> clock buffer/fanout -> A1 chips, do you think there will be problems if I only buffer the clock signal from one buffer to all ICs? I'm worrying about signal integrity when traces get long and noisy

- Anyone had any current readings yet? Should I got with synchronous per IC or asynchronous buck?


Thanks!