Unfortunately when I started the design I hadn't heard anything about over clocking Avalons and didn't design that in. I added some head room on the power supply just out of safety. I'm not aware of any higher current easy to swap regulator solution so the 3 options I see are:
1. Just place 14 chips / board. The wasted 2 chip board space isn't much of a loss.
2. Scrub the extra power connector behind the PCIe and add a IR3897 9A reg there to supply 4 of the end chips. This would cost a bit extra for parts - rough guess, about $5 maybe.
3. As #2 but extend the board by about 2cm and add 4 more chips, plus a full 16A IR3895 reg behind the PCIe conn. This would supply 6 chips, with 2 of those taken from current 16, making a 20 chip board. This would cost only a bit more than #2 due to higher board cost and the parts being a bit more costly, rough guess, about $8 maybe, but a more radical design change due to heat sink size also being different.
Another data point - the IR3895 over current protection kicks in at 18A minimum, so how well it behaves at max load probably depends a lot on how well it's cooled. Also, some of the reported power use in the other thread is for control board, 3.3V supply and fans so it could be somewhat less for actual ASIC power.
1. Just place 14 chips / board. The wasted 2 chip board space isn't much of a loss.
2. Scrub the extra power connector behind the PCIe and add a IR3897 9A reg there to supply 4 of the end chips. This would cost a bit extra for parts - rough guess, about $5 maybe.
3. As #2 but extend the board by about 2cm and add 4 more chips, plus a full 16A IR3895 reg behind the PCIe conn. This would supply 6 chips, with 2 of those taken from current 16, making a 20 chip board. This would cost only a bit more than #2 due to higher board cost and the parts being a bit more costly, rough guess, about $8 maybe, but a more radical design change due to heat sink size also being different.
Another data point - the IR3895 over current protection kicks in at 18A minimum, so how well it behaves at max load probably depends a lot on how well it's cooled. Also, some of the reported power use in the other thread is for control board, 3.3V supply and fans so it could be somewhat less for actual ASIC power.
What would be the (estimated) hash rate of those 3 options?
I think Option #3 is probably too radical especially if folks like Terrahash have cases being built
