Chips have zero voltage. It would be possible to set a "cut here" zone to disconnect local comms and solder pads to jump to the next node could be populated by either solder blobs or 0-ohm resistors. That's pretty much how my L-board works - except instead of "cut here" I just don't put a chip on the second pad in that node so there's nothing for it to talk to anyway. With a "cut here" you wouldn't have to worry about pulling chips, which reduces the "tools required" from a hot-air station to a $5 firestarter.
Leaving big fat pads to short around can get dangerous, because if you accidentally short them when you don't want to things could get screwed up ala Prisma. If you've got a soldering iron, knock off the node-level caps and short across their pads. Wouldn't take but a minute.
Total increase in PCB cost plus parts cost plus additional assembly, $0 - sounds like a win to me.
The chips have zero means of regulating voltage. The thing that keeps the node voltages at about 0.8V is that all the chips are operating at the same frequency and doing the same mount of work - they're all pulling the same amount of power, so the same amount of current is going through each node, so the voltage divides evenly just like it was a string of equal-value resistors. If one chip starts to misbehave, you can think of its resistance changing (either up or down depending on the error) which means the voltage across it changes and that affects how much voltage is left over to divide among the others in the string.
If you bypassed one node, you'd have to drop your board voltage by one node's worth. If you went from 15 nodes to 14 but didn't change your voltage, now your nodes get 0.860V instead of 0.800V and they start to cook a bit.
I have been wondering for a long time how the string setup worked reliably without any signs of a shunt regulator across them. So it is only because all chips are more or less doing the same operations at the same time that keeps the voltage divided evenly... Elegant solution to eliminating the need for VRM's provided all the chips have identical tested specs or apparently at least fairly close ones. Is also a dicey solution in that all must chips be doing the same operations so their loads are identical. I do hope that Bitmain is binning the chips to keep all in a chain reasonably matched! I like your idea on adding mosfets to do just that for when a chip goes down. I assume that the bypass FET will be switched on hard for minimum losses? As you said only problem is that when a chip goes down hard ya lose coms from that point. In hardware mode, as you said - give the associated cap a push to pop it off and jumper across the pads. Perfect solution (until too many get tweaked). Along those lines.... Looking at Bitmains spec for the S7 they call for 12vdc OR MORE. Up to 5% more. With the s5 string setup I wonder how much neg margin we have vs stock clock speed? Bitmain had said the S5 could be fed as low as 9.7v when underclocked. On most of my rigs I usually read 12.1x at the supply and 11.92v at the PCIe connectors. The HP/IBM psu's do have a voltage trim/remote sense sooo. Do you know how low the supplies can be set (for underclocking/volting) and how high when compensating for drop across power leads? What pin terminal is the sense/trim input? |
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My take on the s7 and then 'nuff said about it: Ya I will get at least 1 after they start delivering and we hear more about them. As to their pricing... well my first s2 was around $1,250 as I recall and the 1st s4's the same so, not too terrible for first release. I will probably finally retire my last s2 that's on-line and few S3's to free up power for the s7(s). Also have 2 s4's that are starting to act up by dropping boards from time to time...All in all it is a very good balance on power/replaced hash rate but kills me to take ANY perfectly good miners offline  On the hot turbines -- that exhaust fan will need to to watched as most are NOT happy in the hot side and their bearing life tables reflect that. They should start looking at selling the s7 in pairs and use a dual-squirrel cage blower for them. I happen to have one in the shop and will do just that  We now return to our regular programming. |
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<snip> Having that top chamber with a fixed separation does require more disassembly in order to get cards in and out. Hm...
<snip>
Not if the chamber is part of the top of the case. To me easiest way to hold the PSU's is in a sleeve that is part of the case and welded to the rear panel. That sleeve could also serve as a mounting point the power backplane. Thinking on it, having the sleeve as part of the top as I mentioned earlier means longer cables from the PSU's to the boards and not good... |
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As it stands it looks like the PSU's will be sliding into a sleeve spot welded onto the case lid so it should be an easy change to use other supplies... And again, since the hashboards use PCIe power connectors, this should not be a sticking point. After all, gotta leave _something_ for folks to tinker with  |
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Can't disagree with that. Aside from the redundancy aspect not sure why Sidehack is hell-bent on the DSP1200's but that is what is currently on the board so we follow his lead.
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heh heh heh, ja I still like an external power bank but if they fit, well why not keep them(semi) internal. As for converting to using an external power rack, would be just as I do now -- run heavy gauge power feeds to split into short PCI cables near the cards. No use of the PSU adapters needed. Since the cards use PCIe for power in - is a non-issue to me at least.
As for mis-matched supplies, THAT is a problem but should not necessarily be yours... Drop-in replacement DSP1200 supplies abound with many sellers doing Amazon next-day Prime. Or, just have a few from a multi-pack buy kept as spares. One has to draw a line somewhere.
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THB, I feel screw folks that would want to use ATX supplies at these power levels. Use them on the possible 2-blade s1 style modules. Load sharing makes things so much easier. The HP supplies and their ilk are still pretty damn easy to acquire in multi packs and cheap.
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<snip>
Am I missing something about PSU layout? The fan on the PSU pulls air in through from where the edge connector is right? And if the edge connector is closer to the top of the case than the bottom, their is a metric crapload of room below for the any parts that need to hang down farther. These parts are also directly in the intake path of the PSU. And the edge connector for a slot adapter can still be nice and high for mounting to a backplane that's up on top of hash cards. The fibre mat protects the pins from shorting, and you could build in some struts between each PSU slot to give the case top resistance to being crushed. I think I'm missing something here with the PSU orientation....
ref https://i.imgur.com/rbcz0pw.jpg for a good look at the backs of the DSP1200's. 7.2kw worth Very much like the psu's sticking out. Frees up apparent case depth for the power adapters. Highly approve of forcing load sharing. 1 (in this case 2) +n _is_ what the supplies were designed for after all... Another advantage is that the AC end of them happen to be the hottest parts of the case so good that it's catching the outside airflow instead of making their contribution inside the case. |
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<snip> Good power connectors are through-hole parts, and unless a lot of care is taken to make sure things are durably insulated, it wouldn't be hard for something sitting on top to flex the case lid into those pins and short something out.
Good concern but not to hard to take care of. Use a strip of electrical grade fibre paper contact cemented to the case area above the bare points. |
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It's only common at the breaker box and in the main supplying the box, NOT in the home itself.
NOT the same thing.
Having does more than a little rewiring over the years, I was FULLY aware of how power commonly arrives at the breaker box - but you can't plug a miner into a breaker box much less a main supply.
And how many typical homes have rooms wired for a >24A load between 3 circuits using standard 110/120V outlets? You're talking about having a 2600+W miner that is power-able in the typical home on 15A 110V circuits without re-wiring or a spider nest of extensions cords, keep dreaming. My point is that 240V can be had for those serious enough to want this miner in their home, otherwise wait for the smaller S1 formfactor miner and power it with ATX. Even the S4+ went 205+V for input, likely because they had too many PSU failures with the S4's on 110/120V, it is inferior in all ways for powering PSU's. You can't say 240V is not common, because it is "at the breaker" as you said, it just means extra work and/or expenses to be able to utilize it from the panel, 3-phase on the other hand is not common in North American homes. There's a difference... If i'm not mistaken this miner is being designed for rack-mounting, efficiency and power-density, I'm not sure that people who rent their home is the target market here. The fan noise alone on this thing will probably make it prohibitive to have in a typical home anyways. Agreed. This point has always struck me along the lines of someone wanting a good size welder or ceramics kiln at home -- sure you can do it. After you put in the circuits to feed them! If you want something powered from 110v 15a then one must accept the limitations (smaller units) that come with that. |
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<snip> The nice thing is that having the PSU's at the front of the miner reduces the bending moment on the rack mount ears that you would get if the weight was all the way in the back. So it could probably be done with just a 2 post rack. Watercooling might get heavy but thats up to the end user to figure out.
Only very light equipment is held only by the ears. Anything over a pound or 2 and deeper than a few inches MUST be supported by a sheet metal shelf and the ears are only to hold it in place. 1 shelf - 1 piece of gear. eg http://www.budind.com/view/Rack+Equipment/Server+Rack+Open+Rack+Assembly or http://www.budind.com/view/Rack+Equipment/Four+Post+Double+Rack with the shelves in it. While yes you could stack a couple miners per-shelf if soon becomes a pain when the one on the bottom has to be pulled... I have more than a few cases in the 10+ pound range that are held only by the ears - longest ones around 24" deep. The ears can be QUITE strong, and as short as the case Sidehack is proposing is, it could probably hit 15-20 pound range with zero issues. My Nikko Alpha 3 is 4u, over 30 pounds, about the same length he's talking, the power transformers are in the BACK with the heat sinks hanging OFF the back, and that rack mounts just fine (the front panal is bloody near a quarter inch thick though). Dunno where that "must use a shelf if more than a couple pounds" nonsence is from, but it has ZERO basis in reality. You've never shipped racks loaded with equipment or made equipment that has seismic ratings have you? Our company does. Try just using the ears even with thick front panels (vs ears just bolted to the sides) and it's not pretty opening crates. ref https://www.youtube.com/watch?v=cJVr94drRIs (not ours but is a clear example of what the gear can go through) Point is shelves take up very minimal height and make life a lot easier when installing/removing gear. |
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Ja +10 Something to consider is wire routing from the PSU's. Even direct soldering to the output lands needs some room, using 10ga main leads from my HP's is about 2" https://i.imgur.com/rbcz0pw.jpg. Split out as many 16ga leads right at the lands should be fine with an inch or so. Add a breakout card and it tacks on about 1.5" or so. There is pic of what I mean in that collection I linked to on Imgur. |
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I'll measure what the blade size is in my AMT rig tomorrow. They marginally do it with a lot less air then you will be moving. I dismember the blades being pert near the same size as Ants, maybe a tad shorter and longer.
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I say stick with 7x300w. Well within the range of using PCIe plugs and gives more space to fit PSu's and any air routing they will need. Und ja, selling the smaller stand alones not a bad idea as like you said, end caps would be almost dirt cheap to have punched/bent. Now sizing the board to fit S1/3/5 sinks.... Shades of the S1/S3 upgrades  I did 2 of them, interesting exercise but thass about it. Better to buy ready-made. |
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Thinking about my AMT A1... Is a later Dragon clone and has 5 cards in it with room for 2 more. As the pics in my imgur link show the hash boards make a nice - package. Anywho, it is pulling 1,300w from the wall giving 250w/blade assuming reasonable efficient psu. Took out the 120mm turbines it came with and I put in 3 Cosair SP-20's. In a biz office is quiet and runs @ 55C inside.
Just a packaging reference point as you are shooting for moar power and ergo higher CFM/louder fans.
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Ja
I was wondering about the S1/3/5 thing. Good general form factor to work with per-blade but -- since the blades are going in a case you should be more concerned about how they can be packaged in said case.
Now, certainly doesn't mean one can't slap on endplates and make smaller modules from the blades but doesn't have to fit the org S-series endplates. Hell, turn the endplates around and just call them fan mounts.
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Agreed. Anything that is SMD is very easy to dislodge with inadvertent handling. 'specially large SMD caps. popped a couple off shuffling boards around while modding s1's  |
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I gotta agree the 2nd sinks don't seem to help much. I got an S5 with 1 card that has the Bitmain supplied secondary sinks and the board runs the same reported temp as all the others. Measured main sink and despite the additional chip cooling is same temp as others so... Doesn't seem to make much difference (on a S5).
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heh heh... set up a peta farm somewhere and use the heat to setup a spa with heated pools.  Hell, I'd think that even a couple 100kw of otherwise wast heat would make that feasible. Hmm... For the record -- if someone runs with that idea I'd love some of the proceeds... Wallet 14DdoPoEKiWQQj3WdLShbm6ppvm8349Hto You heard it here first! |
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Just measured one and is a from surface of board to the inside folded edge of an S5 endplate is just over 0.75" (prolly an even mm distance?)
I'd stick with the 1/2 inch for electrical safety and to allow some airflow outside of the sinks.
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