Request for Discussion: proposal for standard modular rack miner

[NotFuzzyWarm]

^ ^ fan type and space between them and the sinks should be perfect  

[1715159959]

1715159959

[1715159959]

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[sidehack]

Actually, the more space left between the rear of the board and the back panel, the easier it'll be to handle plumbing from waterblocks. 1" from board to fan and 1.5" fan makes 2.5 inches; is that enough room to be comfortable? Another depth consideration is PSU length, which the DPS1200 is about 8 inches but those Emersons are closer to a foot. If there's gonna be backplane for them to socket into, and also room for internal cabling, that's probably a minimum if 18" case depth.

I'd be a little leery of stacking PSUs in front of the hashboards. It might work for DPS2K (and that's a nifty setup; most of my big DPS2K installs here at the shop powered Tubes and Prismas which didn't really have the cooling overhead to add that kind of additional heat and airway restrictions) since air'd blow right through but any solid supply like is more common would block a lot of air. I mean there's probably a way to do it that isn't entirely stupid, maybe mounting the front fans internally and behind the PSUs, but then you need more gap for air to get around them and with more than one PSU on top of another you're really eating into your intake path.

It'd be really nice to fit an eighth blade in there, but I'm not sure if there's a better way to mount PSUs (without going full external or significantly changing case dimensions) that gives the heatsink space and also adequate airflow.

[Witrebel]

Yeah I realized today that depth wise I'm not really rendering to your spec.  I'll get that tweaked this evening probably.

regarding the fans/grills, I assume by rear panel you refer to is the panel that I currently show 3 fans on, and you are saying that instead of a panel with 3 holes, you envision an open wire mesh. It seemed like there was some concern that something like that ingesting hot air from the isle through the wire mesh due to the negative pressure in a strictly pull fan configuration.  If you want it like that then I think you may need the front fans after all.

As I have it laid out, you would intake through what I called the "front" which would be your cold isle, and exhaust through the rear to the hot isle.  Is this the "standard" flowpath that you guys run in your farms?  Just wanna make sure I have it straight it my head.

Also, for the sake of the discussion, are you okay with going deeper so long as it doesn't involve any more than the standard S1 ~10 card in terms of "hash cooling flowpath".

If we could go to say 24" deep max, I could probably get something pretty slick laid out.   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.

[chiguireitor]

Having plumbing + Fans on the backplate would be amazing, as the S5 is known for its need of having fans anyways because a lot of heat is dissipated through the ground plane of the chips

Sidehack, do you think you can hand me the DPS1200 or the DPS2K measures so i can take Witrebel's design and rapidly iterate over it to find ways to fit them?

The only problem i see with the DPS2K is the lateral cooling they need, how would you handle that on this current design?

[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...

[sidehack]

If I were using DPS2K I'd wire them up externally, probably with dedicated fans.

DPS1200 measures are already in here somewhere, as well as I think the Emersons and DPS1200TBA (platinum-rated).

Witrebel, no you've got the back panel right. I meant a solid sheet with circles cut out for fans and then an external wire grille per fan. That should be structural enough for things to be comfortable stacked and if chig wanted to run waterblocks he could pull the rear fans and use the space to run his tubes out without having to take off the back panel (which would structurally weaken).
If we wanted airflow for something like S5 that really doesn't work well without both sides cooled, front fans would be necessary in this case. Yes, taking cold in the front and blowing hot out the back is the standard.

It might just be me but I'd like to limit case depth to about 20 inches. This wouldn't affect most rack installs (where things can be substantially deeper) but a bigger box would cost more to ship and be more cumbersome to handle - and for the home miners we're considering secondarily, bigger isn't always better.

Also, being as the box is probably going to weigh between 40 and 50 pounds, I'm not sure I'd recommend mounting it just by ears. That seems kinda dangerous. From the start we were figuring on shorting the case height by a couple millimeters to allow for rack shelving.

[Witrebel]

Chig - What package do you use for modeling? Do you want/need any source files from my model?

NWF/Sidehack - I didn't realize that shelf supports were standard.  I figured the tolerance on the height was just to play it safe.  Good to know as that frees things up a bit.

Regarding the depth I think I could make a 20 work, but it might not be optimal in terms of flowpath.  I just realized how much info I glossed over in your original post, I get to eager sometimes.  I have some actual work I need to do this afternoon but tonight I'm going to try and rework my first draft to really align with your first post and get the heatsinks/board mounting right. 

[sidehack]

Actually, a lot of the information in the first post is no longer really relevant after changing board dimensions. Board and sink mounting still applies, but PSU placement and most everything else related to power is changed. I guess at some point I should write up a complete revision with updates from the last few days' discussions and link to it in the first post. Maybe I'll have time to draw some diagrams too.

[Witrebel]

Yeah I was mostly referring to the heatsink dimensions, and the double sided nature of the boards. 

I should have a couple of good visuals done up by tomorrow as well

[sidehack]

Heatsink dimensions are out too, since the board size changed. And probably the provision for heatsinking both sides is gone.

[Witrebel]

Hmm,  I was planning on just chopping 2inches off the heatsink length but leaving the "Through hole/tall component keep out zone" dimensions the same.  And I don't see why double siding can't still be done.  With side mounted PSU's it might be a slightly smaller heatsink than you have speced but I wouldn't rule it out completely yet.

 

[sidehack]

If you chop the heatsink down two inches, now you have two inches less board for putting chips on and you're no longer really using the board to its capabilities. The heatsink height and length should be the same as on the S1, with the fin height changed to work within our case. That way you can keep board specs fully compatible. Trying to keep an S5 board from catching on fire when the heatsink is two inches shorter will prove to be difficult.

The way we figured, having that inch at top and two inches on the end (in our original board spec proposal) would allow you to put any controllers and through-hole parts in that space, leaving the entire 4x10 chip field for placement of surface-mount components probably on one side of the board. This makes it pretty easy to double-side heatsink just the chipfield. Since we no longer have that much extra space (as we're now limited to the top approximately 1.4 inches only) for everything through-hole and such, it's more likely for other tall components (specifically not ASICs or low-profile local bypass caps) to be placed down in the chip field, so the majority of designs likely wouldn't be able to accomodate the backside heatsink. With this in mind, it's now up to the main heatsink to dissipate the entire power, even though we've just shrunk it in order to fit in a backside heatsink which will rarely be utilized. Way I figure, might as well just spec the one main heatsink to the fullest size possible and let it carry all the heat possible. A gap between the board and adjacent heatsink would still allow for low-profile per-chip heatsinks when necessary.

The board should be the same dimensions as an S1 board. The heatsink should be the same dimensions as an S1 heatsink, with the exception of fin height. Ignore everything said in the first post.

[NotFuzzyWarm]

As long as we are on the heatsink topic, aside from being aluminum what kind are you thinking of? The thin almost shaved kind ala' Bitmain or sturdier extruded ones like in the Dragons?

If extruded then please spend the extra few cents and have the fins ridged - again like the Dragons used. https://i.imgur.com/lfAr2pN.jpg Them tiny looking ridges double each fins exposed surface area making for damn efficient heat xfr.

That pic is from the AMT A1 1.1THs miner I have. One of the few actually delivered. Eventually. 7mo after advertised and emailed delivery date...

[chiguireitor]

As long as we are on the heatsink topic, aside from being aluminum what kind are you thinking of? The thin almost shaved kind ala' Bitmain or sturdier extruded ones like in the Dragons?

If extruded then please spend the extra few cents and have the fins ridged - again like the Dragons used. Them tiny looking ridges double each fins exposed surface area making for damn efficient heat xfr.

The shaved bitmain heatsinks are, in fact, better at dissipating heat than the extruded ones, contrary to what one would think.

I have both models (from the 7th batch) and the extruded heatsinks are considerably warmer than their "shaved" counterparts.

[sidehack]

That's not really my field so I'm not sure what's best. I'd tend to lean toward something fairly sturdily extruded on account of the heatsink fins will be a mount point for things, and I doubt any screws tapped into the shaved sinks would be terribly reliable. If someone with more experience in heatsink design might chip in some opinions would be good.

[NotFuzzyWarm]

added pic above ^^ https://i.imgur.com/lfAr2pN.jpg
What the hell, all pics of AMT's 1.1 THs miner http://phluph.imgur.com/all/
Built solid as a rock and has been running 24x7 since August 27 '14

Ja the shaved sinks are better but a lot more expensive to make. Main cost would be initial tolling charges as I assume they start with thick straight fins and multiple mill them thin then press through a curving die. Damn pricey to setup sizable production for but of course in the numbers Bitmain use I'd think is almost a 1-time for them. (Must keep a few shops damn busy in Shenzhen...).

No if's and's or but's the thicker sinks are also great mounts.

[NotFuzzyWarm]

Ever look at Wakfields site? Ja can be pricey but still at least a good reference.
Link to full up custom design assuming you know some specifics http://www.wakefield-vette.com/company/contact/build-your-own-air-cooled-heat-sink.aspx
General extruded sinks catalog http://www.wakefield-vette.com/products/natural-convection/thermal-extrusions.aspx

No I don't work for them but for almost 40 years do design industrial laser systems and know a thing or 2 about handling multi-kw power and cooling

[NotFuzzyWarm]

Slightly OT but for ^^ above reasons am also a huge fan of liquid cooling using cold plates. Not really worth the time/effort/expense for 1 miner at a time but -- start building a farm and whole 'nother story. Very easy to move as many kw as you want from the equipment to outside. Well worth the cost of plumbing/dry heat exchanger/fan and large pump. Aside from maybe in the Middle East, with the operating temps miners like don't even need refrigeration.

[Witrebel]

Is 0.5in the absolute maximum height that a secondary heatsink can be to retain compatibility with all S1/S3/S5 chasis?  If not what is? 

[NotFuzzyWarm]

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.