Topic: Request for Discussion: proposal for standard modular rack miner - page 5. (Read 9613 times)

If you put the card nearest the PSUs with its non-sinked side up against the wall, it'd be up against the ducting and get good airflow. That might choke air to the heatsink on the card on the other end if it doesn't have good fan exposure.
Conversely, if you can maintain half an inch clearance between the heatsink face and the case wall, the gap won't be too much different than an S5 board inside its plastic side panel and the fan exposure it gets in the stock chassis.

I'd be more in favor of a 4U height with 7 blades, yes. That actually does power a bit better too I think, if we want to limit 300W per blade we have 2100W of mining and potentially another 100W in fans and controllers for 2200W total. 8 blades at 300W makes 2500W total, so your stock power dissipation is more than two 1200W PSUs are rated for. If you wanted 8 blades and reduce the power below 2400W (say, back down to 2200W, still 92% of rated PSU) you're at 262W per blade. That's right about the expected per-blade power dissipation of an S5 at stock settings, but not near what the machine can actually handle.

What would we rather have - 7 blades at 300W, or 8 blades at 260W? If the smaller heatsinks for 8 blades are actually still capable, with the proper fans, of safely handling over 300W each (which would be an overclock-at-your-own-risk level for sure, and our 30x BM1385 board would have an expected top-clock of about 320W, nominal clock more like 230W) I certainly wouldn't complain.

One thing that occurred to me is, if we're already building boards and sourcing heatsinks and fans, we're pretty much just endcap frames away from building an S1. There's no particular reason to require the heatsinks from the rack also work as standalone S1 replacements except that acquiring bulk quantities is already done.

Gotcha, admittedly I'm still scheming for how to make 4U + internal psu + 8 cards + s1 compatibility work.  I think one of those variables has to change.  Safe to say you would prefer 7 boards 4U over 8 boards 5U?  Assuming both had internal power?  

One thing I am getting a little hung up on layout wise is the asymmetry.  In an S1/S3/S5 the boards are mirrored and symmetrical, so nominally they both lay in an identical flow path and identical cooling.  If we go with a single sided heatsink and simply pattern the cards 7 or 8 across, the flow path will be different for that first card that is up against the wall.  You could center everything and leave some space on either side so that although asymmetrical, you still have good flow all around.  But that would eliminates the possibility of PSU's on the side of the case, and makes having internal supplies at all quite tricky.  

Do you think that it matters at all?  That first card having its non sinked side up against the wall?  In reality it may be a non issue, it just looks wrong to me visually when compared to how the S1-5 is laid out.

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  

The actual Bitmain heatsink looks to be 1.5 inches.

If we have a 17.5 inch case and 3.5 inches is PSU, that leaves 14 inches. A practical upperbound is 2 inches per hashboard, meaning heatsinks and the clearance between them in which your PCBs will live. Mind you those are approximate, as this ignores metal thickness for the case and such. The actual heatsink will likely be less than 1.5 inches tall, unless we want to compress the 0.5" clearance between sinks. Reducing that clearance to increase heatsink size will increase power dissipation potential of the sinks slightly, but also can make PCB design more touchy and increases the risk of damaging a board during installation or removal. Everything's a tradeoff.

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).

Okay, fair enough.  What is the max main heatsink depth that would be compatible with the S1 chasis then?  Is that where 2inches came from?  Just looking for all the upper limits so I can play with layouts.

I am still of the opinion that a secondary (short-side) heatsink isn't really worth the trouble. I've mentioned half an inch between the face of one heatsink and the fins of an adjacent, which allows for PCB and some tall SMD components with clearance. This side of the PCB could have individual chipsinks glued on, but I don't think I'd worry about writing an actual full-size secondary heatsink into the spec since I'm guessing most every board implementation would have components near the ASIC which are taller than the ASIC.

For reference, see what they did with the S5+

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!

Amen to that! If only the C1 style would have picked up steam (No pun intended), it would be one of those situations where you buy once cry once. Water cooling would be the real beneficiary of standardized, modular designs like we're discussing, because you can size the heat exchanger/pump/fans as large as you need, Reuse it and the real savings would come from mass deployment (assuming water blocks are cheaper than heat sinks and high powered case fans in bulk). Even with 10kW of miners It would be worth it I think.

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.

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? 

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.

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

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.

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.

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.

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...

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.

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.

 

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