Topic: [CANCELLED] Project Caterpillar - Open Source 3RU DIY ASIC Miner - page 4. (Read 17461 times)

Hi,

Can I leave a suggestion to better optimize the cooling design compared to Avalon's boards?

I'm not very familiar with the packaging used on the chips but usually if they are not flipped chip, like BFL ASIC, you can still cool them better by having the heatsinks on top of the chips instead of cooling through the PCB. For instance:

https://bitcointalksearch.org/topic/avalon-recondition-212090

In this thread one can see the Avalon's cooling system wasn't exactly well applied (I would call it a disgrace) and improving the thermal transfer yielded no more than a couple of ºC improvement - the PCB can only transmit enough heat.

There seems to be some amount of disinformation on the thread about what temps the chips can withstand, quoting Yufi Guo at 100ºC. This is nonsense. The chips can and will work at that temperature but the metal fatigue will be very high and the chips will no doubt fail a lot sooner than they are expected to. Then there's problems like thermal cycles in lead free solder which compound or may be the may cause of problems.

Hope to keep hearing back from this project. Very interested in rack mount devices.

visio versions of the backplane and tray diagrams have been updated on the site:

Thanks!

I'll PM you the vector if you want to use it.

Simple, but very cool! I like it.

very interested in your 108GH/s unit.

watching

Who needs a logo? 

http://i.imgur.com/Yc164xB.png

Ok, a mate that's a bit better at Visio than I am will spend some time on the diagrams tonight or tomorrow.

My 7 year old being able to draw better than my is irrelevant :p

At this stage I'm just trying to get some information posted, I'll worry about cleaning it up once the schematics and pcb design is well underway.

Thanks for the feedback though, it is appreciated and has been noted!

I would suggest to use are more readable font, no baby-blue background and
pleeeeeeasee use software to draw some nice images for your diagrams
... this looks like an art project of an 7 year old otherwise ;-)

I have started a web page and loaded some basic information at http://cryptominer.org/caterpillar/

This seems like a great project. Good luck with it

I've drawn up the block diagrams of the tray and backplane and will get them online shortly. I've spent the weekend (between children's birthday parties and stuff) crash-learning about CPLDs to work out if they will be suitable for handling the communication with the ASICs.

Diagrams and things will be posted on cryptominer.org once I get a moment.

Thanks for following!

any updates?

OK, to post an update, I don't have a lot entered into the computer as yet - I'm still planning out a lot of this, but:

I've pretty much settled on the Norco RPC-3016/3116 case for the initial unit. Need to aquire the chassis so I can check the backplane will be suitable however. I already have an RPC-4120, so I like their cases.

The backplane will be a pure USB data and power distribution backplane. Each miner tray (a larvae) will include the voltage regulation from 12v and microcontroller for the 24 chips on that tray. The board will be 'upside down' in the tray, with the ASICs and most of the SMT components on the bottom and the heatsink and inductors/electrolytic caps on the top.

I'm planning on using a PCIe4x connector on the backplane and a straight card edge contact on the larvae. Each PCIe pin can do 1.1A, so with 50W@12v being 4A, I plan on using about 10 contacts for the 12V power rail so each pin is well under 0.5A.

I've found a suitable copper heatsink - HP c-Class Blade CPU heatsinks which can dissipate the heat from a 120W CPU with the forced air cooling in the HP BladeSystem chassis. Our airflow likely won't be as good as that, but we should still have decent airflow.

I've started work on creating a specification for the location of the connectors (similar to how SATA is a spec) so that it should be possible to put the larvae into any hotswap bay, assuming a suitable backplane is created.

All of the design files will be loaded onto GitHub once I actually get them typed up.

Oh, and 100th post 

This sounds like an interesting project. Would definitely be interested in watching your progress on this.

Good luck

It's probably worth updating the top post to make it clear that one of the design assumptions is good ambient temperature such as in a data centre.

Thanks, it was quite deliberate

Now we just need to prove it.

love the name!

Heh, perhaps

One of the biggest unknowns at the moment is the heatsink, I'm trying to find one that has a base about 6-7mm thick and fins about 15mm high that has a themal resistance <1C/W. If we can find something to fit those requirements, I dont think it will be a large issue - this is for hosting in a data centre (so good ambient temperature) and each tray would only get up to around 60-70 degrees. With good airflow in the chassis, it should be managable.

Fill the case with mineral oil and add a pump + radiator