- One String - a novel bitfury miner design -

[cscape]

Oh, so the cost savings is in the parts list, not the actual power supply.

Correct. You still need a 12V power supply. Each card draws about 2-2.5 Amps, depending on the exact voltage.

[intron]

Ok, so the selling point on these isn't so much the hashrate as the lower cost of the power supply? You are losing me there. can you give an example of a typical power supply used and a lower cost alternative? I'm not sure what we are talking about.

Just as an example, take a look at the HashFast board: almost
50% is taken up by the DC/DC converting circuitery providing
for the low voltage/high current the chip needs.

In a string design this DC/DC conversion is no longer needed,
so taking up no PCB area and not adding to the Bill of Materials.

intron

[cscape]

And it's not just the cost of the components, but also the availability of some of the more exotic ones.

Another factor is the circuit board design. The fast switching DC/DC regulators typically require at least a 4-layer board for good performance. The One String design uses a cheap 2-layer board.

[gmaxwell]

Might be a more interesting design if the chips were priced anywhere near the marginal cost of manufacturer, but with them priced like they were solid gold— the cost of the additional electronics and the reliability concerns may outweigh the benefits.

[cscape]

These boards don't have additional electronics. On the contrary, a lot of the expensive components have been removed, and the 2-layer board is cheaper too.

[gmaxwell]

These boards don't have additional electronics. On the contrary, a lot of the expensive components have been removed, and the 2-layer board is cheaper too.

Yes, I know. I was attempting and failing to say that the because the chips are so costly the additional electronics are not that substantial, and considering the reliability concerns the efficiencies gained may not be worth it.  E.g. you save $x on support electronics but increase the failure rate by y% then if its a win or not depends on the price of the chips.

E.g. if chips cost a million dollars a piece and you save $20/chip on electronics at the cost of a 0.01% increase in failures its not a win.

[cscape]

So far, we have no indication of increased failure rate. The prototypes that we have are rock solid with constant temperature and constant hashing speed. In a couple of weeks, we'll make a few dozen more boards, and we'll see what happens to the failure rate.

[Syke]

I was attempting and failing to say that the because the chips are so costly the additional electronics are not that substantial

That will change. The chips are going down to $5/chip.

[cscape]

That will change. The chips are going down to $5/chip.

Either they will go to $5/chip and lower, or they will not be sold at all. In the first case, you need a cheap, low-overhead, mining board. In the second case, you don't need a mining board at all.

[gmaxwell]

Fair enough.

[rupy]

So when, where and how much?

[RoadStress]

So when, where and how much?

I would like to know that for the 5$/ bitfury chip, because if you are asking about boards, then find out that they don't sell boards. Only the design.

[klondike_bar]

i'm still not sure if my concern was fully answered; what makes this board design work when the H-board string design ended in molten plastic and scorched PCB?

[cscape]

i'm still not sure if my concern was fully answered; what makes this board design work when the H-board string design ended in molten plastic and scorched PCB?

We have a better design

[Pentium100]

The problem with this design is that it requires the 12V power supply to be very well regulated (and adjustable if you want to overclock). Normal ATX PSUs are not that well regulated (ATX spec provides for up to +-5% tolerance on the 12V line (older spec allowed 10%).

On the other hand, I could buy a big well regulated (and adjustable, or at least modify it to be adjustable) 12V PSU and connect a lot of the boards to it. Then it comes to what is cheaper - A standard ATX PSU (I can sometimes get them cheap by taking failed ones and repairing them) and regulators in each board or an expensive PSU and no regulators. I guess the "no regulators" design wins over for large numbers of boards, while the traditional design is better for a few boards.

[cscape]

The on-board 0.8V, 30A regulator would add about $15-$20 to the design. For 10-15 cards, the money saved would buy a good PSU with voltage trim option.

Either way, the cards work fine if the voltage isn't perfectly regulated. They just run a bit cooler under 12V, and a bit faster/hotter over 12V.

[Dexter770221]

So, now it's time for you to design board with parallel/serial connection of chips
PowerMatrix

[intron]

So, now it's time for you to design board with parallel/serial connection of chips
PowerMatrix

We did that already. It's called X-HASH:)

intron

[Trongersoll]

So, now it's time for you to design board with parallel/serial connection of chips
PowerMatrix

We did that already. It's called X-HASH:)

intron

and how did that work?

[intron]

So, now it's time for you to design board with parallel/serial connection of chips
PowerMatrix

We did that already. It's called X-HASH:)

intron

and how did that work?

It takes so many bitfury chips to test it, we were
reluctant to try it. That's why we started with the
smaller strings.

intron