Quote from: tschaboo on June 26, 2011, 08:02:32 PM

Hi,

I don't know too much about hardware, but I still want to comment on a few points:

1.) Power connector: I hate those molex-connectors but the ability to use a standard ATX PSU without hard-to-get adapters is worth going with it. But I also think that an ATX supply isn't the most efficient choice, when you use only the 12V rails. Also they are rather expensive, usually overpowered and need active cooling.

My suggestion: there are a lot of aftermarket notebook power-supplies, from very cheap (http://www.amazon.com/Notebook-Charger-Adapter-Thinkpad-40Y7659/dp/B002BW0MNU/ref=sr_1_1?ie=UTF8&qid=1309117838&sr=8-1 or http://www.amazon.com/Replacement-Notebook-Adapter-Charger-Inspiron/dp/B004FQPGG8/ref=sr_1_4?ie=UTF8&qid=1309117838&sr=8-4) to better ones with higher efficiency. Cheaper, passively cooled, still enough power. Adding such a connector and a 12V regulation to the motherboard might not be too expensive?

Depending on how you do this you might want to plug those things directly into power-hungry mining cards, as the 12V rail might not even need to be regulated. It's only the supply for various other regulators.

Quote from: tschaboo on June 26, 2011, 08:02:32 PM

2.) Onboard controller: I like those embedded ARM/MIPS-CPUs but I think they shouldn't be on the motherboard if they are not necessary. If the USB-bandwith is enough to supply all those FPGA with data, then leave the high-complexity tasks to the Host. And it really doesn't have to be a PC. I have a Sheeva Plug which takes less than 5W and has a 1GHz ARM with 512MB RAM. More than enough I think.

My intention was to use this ARM CPU as the host, and communicate via ethernet from there. No need for a sheeva plug.

Quote from: tschaboo on June 26, 2011, 08:02:32 PM

3.)

Quote from: Olaf.Mandel on June 26, 2011, 06:25:06 PM

The FT2232 operates bus powered (works without having +12V connected).

Since you can't power the whole FPGA-array through one USB-port and we will need an external power-supply anyway, I'd suggest to also power the FT2232 from the power supply. Why? There are potential host-devices that can't even handle the minimum 100mA. For example an Android phone with a modified kernel to support host-mode ... would also be a very power-efficient host.

I don't really see why one would ever want to do that. If the FTDI is the only chip that needs 5V power, bus-powered seems to be perfectly fine to me.