Request for Discussion: proposal for standard modular rack miner

[sidehack]

I'd really prefer to keep a single box with fully modular innards than several boxes that stick together.


"For the stacked miner, you could run any 3 PSU's that fit in a 1Ux6U space, or any space you allocate on the shelf really.
If using backplanes and hotswap, you could ship the PSU's out of the bays so that it fits in a smaller box."

I honestly have no idea what that means.

If we determine that an S1-sized heatsink can cool 260W with 1.2" fin height instead of 1.5", I'm pretty sure we can then fit 8 S1-compatible cards with 3 PSU (up to 12" long) inside a single 4U case no more than 20 inches deep.

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[Witrebel]

End of the day that's your call.  I'm just curious what leans you that way.  And for the record I don't see "many" boxes, so much as 2 identical 12" boxes that have modular innards with eachother. So you can could still source one box, one chassis, and build it up as you see fit for sale in various configurations, it just affords you alot of room to play with and keeps shipping size down.  But yeah just a fringe thought, one box is clean.

After a long few days at work I think I'm better at modeling than I am at articulating, I can see why that would be hard to follow.  

This is along the lines of what I was suggesting could be done if someone wanted to step outside of the DPS-1200 size envelope.  Basically just hang a PSU outside of the box.  
I thought you had referred to this size PSU as a 1Ux2U psu.  So I was saying that 1Ux6U across the top gives you the basic PSU bay envelop, and provided there is a backpane to match the model of PSU, you could really stick just about anything in there that will fit.  It's just going to look funny from the rear.  



But yes, I can see how you could pull off 8 * 260w in a 20in case. 

I just feel like this places an unnecessarily low thermal bound on a 4U case. Granted 2kw isn't "low", but unless you water block it you are pretty much capped.  Maybe I'm biased because my particular situation doesn't really require efficiency.  So perhaps a 2kw thermal ceiling is pretty high all things considered. 

[sidehack]

Some folks have trouble keeping 1.6KW cool in the 3U S4+, which translates to 2.13KW in 4U (yeah I know you can't directly scale like that, but for the sake of argument). 7 blades at 300W is the same heat as 8 blades at 260W; the first thing I'd do if I built an 8-blade is push it to about 320W per blade and see what breaks first.

Having PSUs hanging out the back looks goofy. But - BUT - if they're secure, maybe it's not so bad. I'd be worried about trying to slide the case forward and a cord hanging and pulling the PSU out of its slot. But if they can be secured in a non-clumsy way, that might be okay. Certainly worth considering. That would also remove the need for internal mains wiring - you now can no longer run it off a single C19 cord, but that's probably okay.

The only problem with encasing the entire front in 8U blades is where does the controller go? But of course you could partition off 1-2 inches along the side (basically what would be left over from 3 120mm fans comfortably laid out) for the electronics. And it wouldn't be difficult to build a snap-in panel to fill a drive bay or two with power jacks for external supply connections.

Could work.

[QuintLeo]

If by "sizing around one specific PSU" you mean "any of half a dozen existing PSUs which can be acquired new or secondhand will work without significant mechanical alteration" - since the 1Ux2U server PSU is a very common dimension - then yeah, I'm sizing around one specific PSU.

I also don't really consider 4U rack to be a small case, given that it's a taller dimension than any decent rackable gear built in the last year.

Home miner is a secondary consideration for rack gear.

 I didn't realise that DPS1200 was 1ux2u. Size objection overruled by additional fact input.

 15" deep is VERY SMALL for a 4u computer case. 20"+ is a lot more common. The only 4u cases I've seen that were under 18" were for audio gear, and ONE computer case designed for a microITX motherboard based server.

 If it's intended for commmercial specific, I'll point out that EVERY Bitfury rackmount miner appears to have been 6U and somewhat longer than you're aiming for.
 IIRC at least one of the Avalon rack mounts was also 6U.

[QuintLeo]

220 isn't anywhere near as common in the US as 110. Most HOME miners have ONE 220 outlet available (for their dryer), many don't have any.
 You pretty much have to OWN your own home to be able to add 220 outlets, and most folks have no clue how to wire them up - at which point you're talking expen$$ive electricians to be ABLE to add any 220 outlets to your home.

Actually 220/240V is the MOST common power supplied to homes in North America.  It's called split phase (single phase), and nearly all homes are powered with it in both Canada and US.  They split the single 220/240V phase into 2x 1/2 phases of 110/120V each at the panel, meaning anyone can have a 220/240V outlet made up by combining opposite phase 110/120V circuits.

 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.

[QuintLeo]

<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.

[Finksy]

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.

[NotFuzzyWarm]

<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.

[sidehack]

240V is typical to homes, but is in very limited use inside homes where 120V circuits are substantially more common. Would it take a bit of work to get a sufficient 240V circuit for this machine in someone's house? Very likely yes. Is that impossible? Very likely no. Y'all are both saying the same thing but somehow disagreeing. How the information is packaged doesn't matter as much as the information itself.

I would not ask anyone with a 30lb 20-inch-deep case to ear-mount only.

I think 18" case is the shortest design that's really been considered so far. S2, S4, S4+, Avalon2 are all in that neighborhood.

I'd like to keep considering Witrebel's idea of having the PSUs short-socketed with part of the supply hanging out the back. That does offer a solution to using differing lengths of supply (so long as they can fit in a 1Ux2U hole), fits 8 blades with sufficiently large heatsinks, provides empty space in the airpath for turbulence to normalize (which can also be used for piping in a waterblock installation), allows for ready access to PSUs without requiring partial case disassembly, and doesn't somewhat arbitrarily increase case volume with deadspace (which would increase material and shipping costs). The layout is also more conducive to a snap-in solution for external power access. My only real concern would be making sure the supplies were secured in their holes, which will require some work since the latches are always at the back and supplies aren't always the same size.

[NotFuzzyWarm]

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.

[Witrebel]

Before I mock up any specific mechanical solutions for attaching PSU's securely that protrude from the rear, I'd like to define the objective.

I don't know much about PSU interchangeability so if you could clear up a couple things it will help the brainstorming. 

Do PSU's have any standard for the output blade?  As in, if you spec the unit with a DPS-1200FBA and its internal and flush mounted, and someone wants to put in a DPS-1200TB, does the unit interface with the same socket on the backplane? Or would each PSU need an entirely separate backplane? 

I ask because it would help to know how you plan to offer the unit in its stock form. 
What upgrade/modification paths you want to design specifically for and support. 
And what upgrades/modifications you want to anticipate and allow for, but leaving actual excretion up to the end user.

This would shape the types of solutions that make sense for securing the PSU's IE:

Stock unit with DPS-1200FBA supplies, with optional adapter/guide that interfaces a different length PSU to the same internal fastener, this would mean same backplane.
Stock unit with DPS-1200FBA supplies, with optional PSU bay section that includes a new backplane and mechanical solution for fastening the PSU unique to some other model of PSU.
Stock unit with longer PSU supploes and a stock secure method for attaching those PSU's, with an optional method for attaching the shorter DPS-1200FBA. 

Basically I think that actually securing a PSU in a socket is relatively trivial.  What isn't trivial is picking the most flexible solution that is compatible with everyone's needs and not overly expensive to produce.

[sidehack]

The backplane pretty much just needs to be sockets fit for the PSU (which Emersons and 1200FBA are quite incompatible, not sure on the 1200TBA) and a few signal lines for load balancing, turn-on and PGOOD flags.

As you mentioned, feasible options would be to either construct interchangeable backplanes, specific to the model of PSU but mounting up to the same space, or to spec a single standard backplane and make slot-in adapters to go from the stock PSU to something else.

I had previously assumed using a different backplane for different PSU, but adapters isn't a bad idea. That reduces the replacement cost if you want to use a different PSU. The problem is, it allows different models of PSU to run on the same bus - which depending on their means of load-balancing and stock voltage setpoints, could be fairly disastrous.

If we make a stock channel size for the PSU (based around the largest practical supply) and when you buy a kit for a different PSU it comes with the power socket adapter and maybe a spring insert that grips the supply and fits tight to the bay slot?

One thing I thought of with your model is, the PSUs are upside-down. That does make the case depth a bit shorter because now the backplane can ride in the space above the boards, but I'm not sure how safe that'll be. 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. That can also cause mounting problems and airflow restrictions to your supplies.

[NotFuzzyWarm]

<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.

[sidehack]

So now you don't short your pins, but the potential for mechanical damage is not decreased. You also have no means of getting any standing parts out of the direct airpath of your supplies, since the backside of the board (where you could put any tall parts that aren't the PSU connector itself) is up against your steel ceiling. Immediately below the potentially somewhat congested airspace directly in front of the PSUs, however, you have about five hundred cubic inches of empty.

It might make the case a bit longer to put connectors at the bottom, but a board could be built that doesn't interfere with hashboards and doesn't pose a risk of shorting or mechanical damage to the case lid.

Also... here's a question. If we allow for multiple PSUs in redundant configuration, is it possible to also isolate PSUs to particular subcircuits so different PSUs could be used in non-redundant (which is to say, not load-balancing) configuration without a substantial hardware change? That needs to be addressed if someone wants to use external ATX supplies or any supplies, internal or external, that can't be put on a common rail.

It might be simple as having three separate internal busses (3 board, 3 board, 2 board + controller + fans) that would be heavy-jumpered for a shared bus or remove those jumpers for separate rails. There's probably other ways to do it, but that requirement will partially dictate backplane and internal power design.

[Witrebel]

I hadn't thought of using slot adapters, not a bad trick. It sounds like the backplane having integrated load balancing circuitry is a foregone conclusion?  I ask because there may be some small number of people wanting to piece together systems using different PSU's, and this rules them out if you gang the output from the supplies to a single 12v channel supplying 8 cards in parallel.  Perhaps this is where a factory wire harness option comes into play.  

Lets explore the standard backplane with slot adapters.  Oversize the PSU bay slightly as you mentioned to accommodate all practical options.  The solution to mismatched PSU's can be in the form of a mechanical system. Something intrinsic to each flavor of power socket adapter that prevents two flavors of socket adapters from being inserted adjacent to each other.  Not entirely sure how this would work for stopping someone from putting PSA A in slot 1, no PSU in the slot 2, and PSU B in slot 3.  But at that point someone is intentionally trying to be stupid.  

Edit:

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....

[NotFuzzyWarm]

<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.

[sidehack]

If the connector is at the top of the case, the fans are right below the connector. In order to access the crapton of room below, your parts hanging down are directly in the way of intake air to the PSU. If the connector is at the bottom, you can still have parts hanging down but now they're below the PSU's airway in all that open space otherwise unoccupied behind the hashboards. This puts the backplane at lower than the top of the hashboards, meaning now the entire backplane has to be behind the hashboards instead of allowing it to be above them. This makes the case a bit longer (potentially) but also means you don't have to remove your PSUs and power backplane and power backplane mounting framework before pulling a hashboard for servicing or replacement.

If we don't do common-rail we lose redundancy. If we're not concerned about being able to load-balance the supplies, then there's no real reason to do a common rail - which makes using different or external supplies relatively trivial. I would prefer if load-balanced redundancy were still an option, but not if it makes every other option more cumbersome to achieve. It's probably not worth the trouble.

One way it could be done is with an intermediate power block connecting the backplane to the internal cabling. Say you have three PSUs 1, 2 and 3 (and each PSU has three cables to the intermediate block) and you have three board groups A B and C. If you keep cabling between the supplies grouped, so 1 powers A, 2 powers B and 3 powers C, now you can use whatever supplies you want and they never interact. But if you take one cable from each supply and tie to each board group, now you have common rail by default because A is powered by 1, 2, and 3 - and so are B and C. Two minutes with a screwdriver and you can switch between common and independent rails. Maybe there's a jumper on the backplane which ties the current-share lines. This also further modularizes the separation between backplane power and the cabling to the boards themselves.

[NotFuzzyWarm]

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.

[sidehack]

I don't mind screwing ATX folks. But you end up screwing anyone with mismatched server supplies as well. If I got a machine with a down 1200W PSU and I have a different 1200W PSU I could drop in while waiting for replacements to ship and arrive, but I can't do that and now I'm down 4TH because the manufacturer mandated single-rail redundancy but I don't really care about it, well, that kinda sucks. And the point of allowing external supplies (which folks were arguing very heavily in favor of a very short time ago) includes allowing mix-matching external supplies.

[Witrebel]

I agree with sidehack on not mandating either option but providing for both in an economical way.  I think you pretty much have the connectivity down pat with your A B C grouping situation.  This means each rack unit can have a common backplane and wiring harness that can be purchased in bulk. 

I am not sure on the cost differences between a wire harness, a slot adapter, or a terminal block on the backplane, but I think you could also solve the problem of people wanting to go with external supplies. 

You can either offer an entirely new wiring harness for external supplies.
Or you could make the existing wiring harness attatch to the backplane with a connector, such that an additional wiring harness can expose the internal harness to the back of the unit by simply connecting in place of the backplane.
Or you could offer slot adapters with terminal blocks that could be used to adapt any supply to the backplane, leaving the internals hardwired.  This would also allow you to expose P_GOOD and current sharing signals to the external harness. 
A slightly more labor intensive option would be to simply build ALL backplanes with terminal blocks for tying in external supplies.  Although that may impose an un-needed cost on all stock units with internal supplies.  Either way, I think there is alot of flexibility involved with the whole concept of grouped boards tied to a 3 PSU slotted backplane.

Regarding the layout and flowpath for PSU's,  it sounds like there is little need for cooling on components populating the slot adapter?  I'm hearing that you want the most unobstructed flow path into the PSU intake.  How critical is this? How much flow do we need? Can that number be quantified?  I assume it's something along the lines of "Enough airflow to cool 600-700w of PSU waste heat at up to ~35 deg ambient intake temps". 

I would need to work the numbers and run some simulations but intuitively I feel like if the PSU's generate negative pressure in the PSU cooling channel, the flowpath doesn't need to be absolutely perfectly straight. 

I reworked the model with the PSU's flipped.  I focused on trying to maximize the PSU intake tract, again, without knowing how much this really needs to breathe.  As such, I envisioned the power leads coming of from underneath the backplane, routing to the outside, then penetrating through the top shelf to be routed to the front of the hashing cards, where they plug in.  This provides balanced flow to all the PSU's, and it only means a little bit of cabling in the front of the PSU duct.   Tradeoff is you make two seperate areas for the controller, unless they end up living in the hot zone between fans and hash cards.  How hot do those exhaust temps tend to get?  Is it an issue that the backplane compenents are hanging down into that hot zone now? Would they get cooked?  My original thought was that you'd want absolute separation of the hotzone from all other components.  How critical is it that the components above the heatsinks on the hashing card see airflow?  Could they be in stagnant/low flow air? There is alot of space above the fans that could be sectioned off and made into a cooler space, but this would restrict airflow that comes in between the tops of the hashing cards and the heatsinks.





Thoughts?