Topic: ANTMINER S5: 1155GH(+OverClock Potential), In Stock $0.319/GH & 0.51W/GH - page 282. (Read 451266 times)

I didn't want to clog up this thread with these speculations, so i made a new

https://bitcointalksearch.org/topic/m.9922620

Took me an embarrassingly long time to work out where 9v is coming from. There's one chain per blade, two chips per voltage step in parallel for a total of 28, so each gets potential of 0.64v. I'd actually already begun thinking of how to do something insane like that, except I was going to replace the BeagleBong in each with some optoisolators on the SPI chains. Wouldn't be a massive undertaking to get 0.24W/GH out of the things but I don't know how much you'd be saving over the normal DC-DC, or more importantly if it would be worth it or not.

Love to get my hands on their chips and make a higher voltage blade, though I'm very inclined to think that they've bought Bitfury 3 masks.

Dang. I really hope he used an isolation transformer. That's a buttload of chips too.

Novak and I were chuckling earlier today, wondering how long it would take for someone to ground-isolate and stack three server PSUs, and stack four S5 in series to get 9V per machine. The only problem there will be ground loops on the ethernet cables causing your switches to explode, but it could be interesting nonetheless.

There's a post somewhere in the depths of the forums where someone got the Bitfury chips working straight from mains voltage in one huge string. I don't know how long it lasted, but I don't imagine it would have been particularly stable with the Bitfury's internal oscillator and the wildly swinging supply voltage. Absolutely lethal device with rectified mains voltages exposed everywhere, but impressive none the less.

This is the fourth string miner that I know of - the others being the OneString and Yazio (or whatever) boards with Bitfury chips, and the Prisma. I know plenty about how reliable the Prismas are, but not enough about the Bitfury-based boards. (A previous post mentions a fifth design I had not previously seen, so chalk that one up).

klondike_bar's assessment is not entirely correct; the active players in the circuit are voltage and also current. The capacitors at each string node will help balance out brief changes in current (which are natural occurrences with all the switching going on in the chips) to help maintain a constant node voltage, but won't really help much if one of the chips drops out entirely. Suddenly the current path at one node is cut in half, which means that, unless external provisions are made to compensate, the second chip in the node will have to push twice as much current as otherwise expected. This might result in the voltage across that node increasing until the chip is allowing that much current through, which will greatly increase the power dissipation (potentially quadrupling it) on that chip which very well might roast it. The best case would be the chip fails short, in which case you now have an unbroken current path, but with one of 15 nodes out, the rest of your chips' voltages increase by about 7%. If the chip fails open, you now have no current path and the entire board is down.
If, on the other hand, instead of the node voltage increasing until the current draw is in accordance with the rest of the two-chip banks, the current stays low and starves out the other banks, now you have a board which technically works but does not operate stably.
If each bank is provided with an active dummy impedance working alongside the capacitor, the two systems can effectively buffer the node voltages and chain currents to keep every chip functional. If one node's voltage starts to increase beyond what capacitor ripple can handle, this indicates it's not passing full system current and the dummy impedance can open up a bit to allow excess current through, keeping the system operating and the local node voltage at the expected value. If there's a stably controlled system like this in place, I'd have a lot fewer qualms about running one of these boards (we're actually toying with designing one of our own using that principle). I don't really trust unregulated strings as they are, but if there's some node-level regulation at least, it's certainly got more potential for stability and reliability than just trusting the chips to all operate within a narrow tolerance of "identically".

Another thing that's probably not something anyone wants to do, but could greatly assist the reliability of a chained design, is individually fused chips (alongside a controlled dummy impedance). If one fails short and overcurrents, the fuse blows and now that portion of the bank is an open circuit. Your dummy impedance will have to take its full share of the current, so with a chip like BM's where it's expected to draw around 9W you'll need a well-sinked dummy but that's not difficult. If an entire bank goes out, the dummy impedance will have to take the entire load, but it avoids the problem of overvolting the rest of the chain.

https://i.imgur.com/hAss6mY.jpg

Intron tried a stringed Bitfury design too. The problem is that they like to fail short, and when they do all of the others in the string get a proportionally higher voltage. Cascading failure and the magic smoke comes out, or magic black goop in the case of Bitfury's chips. I think they eventually got this one functioning under a slightly different design, but it makes me nervous all the same.

shouldn't

but...

does.

*cough* AM's Prisma chain design:

the fact that it was a


and you didn't open up sales, is a big red flag for me. You must have had problems that you wanted to hide?
why not just open up S3++ sales? I don't understand the logic here. It's not like you to remain so closely guarded.

what went wrong?

it's not the same ASIC, the community haven't tested the string design and I, for one just cannot take anything that dogie will offer us when he reviews, on the simple fact that you are paying him to do so. I have serious reservations about this miner.

s5 is a much riskier design due to the chain.. if one chip dies, the whole board goes down.
I've opted not to order now that I realise they have chained the chips.

If one chip fails it shouldn't affect the rest. The chip schematic has multiple Vin and Vout pins, and the only way to knock out the entire chain would be disrupting the voltage drop across chips. The s1 and the s3 both used chains for the data already, chaining power is the only new thing.

I hope so. I'd like a bunch of upgrade kits for my S1's

Just pay via bank transfer. 

A little promotion of S5:  https://forum.btcsec.com/index.php?/topic/10755-antminer-s5-ot-bitmain/

 

BITMAIN, how often do you update the bitcoin/usd price on your site? current price is 334-335, and your ticker is stuck at 328. for a large order, that makes a hefty difference. i placed an order, and i didn't realize your bitcoin price ticker was not being updated... 

just wondering if the different options will now ship directly into canada. i'm looking for the option that includes the duty fees into the cost of the miners. so i dont get hit with any unexpected costs.

Well, even if it run perfectly well for you, unless you're situated in Singapore where the season are hot, hotter and hottest, there is definitely more chance of a chip failure for where I am. Unless I host them at a NOC but I like to feel and touch my miners. I've got a fetish. 

Just don't buy ...let the other people - like me -  experiment for now ... 

It's my Christmas' gift ...

ZiG

Damn it. I really want to buy but but but but... too many buts.

Someone please help convience me.

Me too...+ pretty Chinese girl inside ...
 

That's why I've asked about parallel current paths (like the FETs on Prismas and such), which can pick up the load slack if a chip drops out. Of course, you also need to not have daisychained comms for that to work perfectly.