Custom FPGA Board for Sale! - page 11.

fizzisist

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Quote from: kano on August 22, 2011, 08:18:30 PM

Quote from: inh on August 18, 2011, 08:53:07 PM

6.8W isn't a lot compared to a GPU but it is a TON compared to these FPGAs that normally run at 3 watts or below. FPGAs are really being pushed in these applications.

Does that affect the expected lifetime of these?
What's the expected lifetime at the normal 3W?
and the expected change to that at 6.8W?

Mining is 24/7 - so those lifetime expectations would be rather critical.

Xilinx publishes some reports on reliability tests: http://www.xilinx.com/support/documentation/user_guides/ug116.pdf

I haven't read through that all yet, but the interesting test is probably the High Temperature Operating Life Test. It looks like they tested the Spartan 6 (XC6Sxxx) at Tj > 125F for 533,351 hours. They somehow scaled it to "equivalent hours at 125F" to 1,161,865 hours. That's 132 years. Not sure how to interpret the fail rate, but it's either 0 or 10%... Either way, I don't think failure is going to be a problem, but please use some type of heat sink. The better that you cool the FPGA, the less power it will consume, just like with GPUs or any semiconductor. We plan to ship the boards without heat sinks, so that you can put on whatever you like. We'll offer a suggested one, that should work well enough without a fan. Increasing airflow with a simple fan never hurts, though.

Quote from: coblee on August 22, 2011, 11:55:20 PM

If I want to give this a try, what's the most barebone computer I can use? Let's say I want to build a dedicated FPGA miner. I can get a cheap motherboard since I don't need PCIe slots. I can go with a small PSU and if I do LinuxCoin on a USB stick, I don't even need a hard drive. If I want to go all out, how many of these can I put on a single motherboard?

The USB bus allows for up to a maximum of 127 devices, so you should just need a bunch of hubs to get pretty much as many as you like. There might be some other issues with running multiple boards, though, because it's never been tested yet, but that should all be worked out in software. The smart thing to do would be to wait until someone confirms that they got multiple running before you place an order for 127 of them

Keninishna

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all you really need are usb ports so I imagine a lot.

coblee

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If I want to give this a try, what's the most barebone computer I can use? Let's say I want to build a dedicated FPGA miner. I can get a cheap motherboard since I don't need PCIe slots. I can go with a small PSU and if I do LinuxCoin on a USB stick, I don't even need a hard drive. If I want to go all out, how many of these can I put on a single motherboard?

When will this be available for pre-order?

kano

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Quote from: inh on August 18, 2011, 08:53:07 PM

Quote from: kano on August 18, 2011, 08:48:31 PM

I was just wondering ... why does a 6.8W FPGA need a fan?

A cheap 40mm fan is like 0.07Amps so about 0.8Watts - an increase is power of about 12% - 12% is a lot.

My 6950's I set to not run the fan when they are under 60degress.
At 350Mh/s they stay over 60degress, but a drop to something like 250-300Mh/s and they will stay under the 60degrees and not even need the fans on.
... and we are talking over 100Watts (350Mh/s is about 180Watts)

Just wondering about the decision to bother to put a fan on it all ...

6.8W isn't a lot compared to a GPU but it is a TON compared to these FPGAs that normally run at 3 watts or below. FPGAs are really being pushed in these applications.

Being pushed ...

Does that affect the expected lifetime of these?
What's the expected lifetime at the normal 3W?
and the expected change to that at 6.8W?

Mining is 24/7 - so those lifetime expectations would be rather critical.

Just wondering.

newMeat1

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Quote

I understand the preorder can be paid with bitcoins, right? Also, what would be the manufacturing date?

Yes, Cablesaurus has always taken BTC. My best guess on manufacturing date (when the PCB order is submitted for manufacture), if things go smoothly, is Sep 15th.

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For me this is a deciding factor. Good job on this!

Thanks. We realized pretty fast that it was crucial

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Does that include the $50 preorder? (ie is the total cost 420+50 or 370+50?) How much would that become if you get, say, 20 preorders? (I assume the same percent discounts apply to the 2-FPGA version and I'll calculate them myself).

370+50. 420 total would be the most that you would have to pay for a single FPGA board. Let us get back to you on the quantity-price breakdown. fizzisist and Li are working on some spreadsheets right now. My top-of-the-head guess is $385 for 20 orders.

EDIT: The preorder page on Cablesaurus still isn't up yet (it's just a test version right now). Expect a post from him soon

dserrano5

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Quote from: newMeat1 on August 21, 2011, 04:04:24 PM

It's $50 to preorder your board (same cost whether you want one or 2 FPGAs). Just before manufacturing the boards, we will ask you to pay the remaining balance. [...] Cablesaurus takes Paypal and bitcoins.

I understand the preorder can be paid with bitcoins, right? Also, what would be the manufacturing date?

Quote from: newMeat1 on August 21, 2011, 04:04:24 PM

2. Only a USB cord and 4-pin Molex will be required to run it (no Platform cable)

For me this is a deciding factor. Good job on this!

Quote from: newMeat1 on August 21, 2011, 04:04:24 PM

- costs less than $420 (likely quite a bit less, especially if we get decent volume discounts)

Does that include the $50 preorder? (ie is the total cost 420+50 or 370+50?) How much would that become if you get, say, 20 preorders? (I assume the same percent discounts apply to the 2-FPGA version and I'll calculate them myself).

newMeat1

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jav-

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Is my understanding correct, that previously the platform cable was used to upload some type of firmware? Is this now done over USB? or what was the function of the platform cable and by what is it replaced now?

That's exactly right. The next batch will only need a USB cable. It plugs into the board and a chip handles the USB-FPGA interface. Exactly what type of chip handles the interface is a trade secret at this point

Cablesaurus

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Quote from: jav on August 22, 2011, 04:29:35 PM

Cool project!

Quote from: newMeat1 on August 21, 2011, 04:04:24 PM

Here are our basic guarantees about the boards:
1. Delivery by Nov. 1st 2011 (hopefully sooner, I left some extra time in case we screw up)
2. Only a USB cord and 4-pin Molex will be required to run it (no Platform cable)

I don't know too much about the hardware side of this stuff, so here are a few newbie questions:

If you would control this from a laptop, where would you get the 4-pin Molex connector from? Do you need an additional AC power adapter in that situation?

Is there such a thing as a USB to 4-pin Molex adapter? Or does a USB port not provide enough power for this?

Is my understanding correct, that previously the platform cable was used to upload some type of firmware? Is this now done over USB? or what was the function of the platform cable and by what is it replaced now?

Thanks in advance. :-)

- I'll have PSU Dummy Plugs in stock which would allow you to power a PSU from basically anywhere without needing to plug it into a motherboard
- I'm not aware of a USB->Molex adapter but the PSU dummy plug would solve such an issue

I'll add some pictures and more details surrounding the plugs soon.

jav

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Cool project!

Quote from: newMeat1 on August 21, 2011, 04:04:24 PM

Here are our basic guarantees about the boards:
1. Delivery by Nov. 1st 2011 (hopefully sooner, I left some extra time in case we screw up)
2. Only a USB cord and 4-pin Molex will be required to run it (no Platform cable)

I don't know too much about the hardware side of this stuff, so here are a few newbie questions:

If you would control this from a laptop, where would you get the 4-pin Molex connector from? Do you need an additional AC power adapter in that situation?

Is there such a thing as a USB to 4-pin Molex adapter? Or does a USB port not provide enough power for this?

Is my understanding correct, that previously the platform cable was used to upload some type of firmware? Is this now done over USB? or what was the function of the platform cable and by what is it replaced now?

Thanks in advance. :-)

fizzisist

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Quote from: newMeat1 on August 22, 2011, 01:12:14 PM

Sirky-

Quote

I wonder what the best way to mount a bunch of these would be. Surely just laying them somewhere cannot be most efficient.

What are the physical dimensions with the heat sink on?

For the next batch, we are looking at a 3.4in x 4.1in rectangle. I don't know exactly what the height will be~ probably about 1.5in with the heatsink. We're definitely gonna put some mounting holes and standoffs in, so you can stack them vertically.

Here's the kind of standoff I'm talking about:
http://media.digikey.com/pdf/Data%20Sheets/Daburn%20PDFs/10-40_1.pdf

Actually, something like this would probably work best for assembling a stack of boards: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=4808K-ND

Maybe Cablesaurus can sell some of these as accessories as well, so that folks can get everything they need in one order.

newMeat1

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Sirky-

Quote

I wonder what the best way to mount a bunch of these would be. Surely just laying them somewhere cannot be most efficient.

What are the physical dimensions with the heat sink on?

For the next batch, we are looking at a 3.4in x 4.1in rectangle. I don't know exactly what the height will be~ probably about 1.5in with the heatsink. We're definitely gonna put some mounting holes and standoffs in, so you can stack them vertically.

Here's the kind of standoff I'm talking about:
http://media.digikey.com/pdf/Data%20Sheets/Daburn%20PDFs/10-40_1.pdf

newMeat1

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ElectricMucus, I finally got some answers for you...

Quote

1. Will there also be a discount for the 3rd+ generation for generation 2 buyers?
2. Will the 1 piece board be upgradeable with a hotplate & some luck?
3. Will the preorder deposit be refundable if you don't have the money (I know that's cheap lol)

1. I'm sorry to say it, but no. The only reason we gave a discount to the first 4 buyers is because they knew that a cheaper version of the board would be coming out soon.

The Gen 2 boards will be pretty well optimized (in terms of $/Mhash) so we shouldn't need to give any extra incentives to buy them. Also, if we promised future discounts, it would be a nightmare for Cablesaurus to keep track of.

2. The FPGA chips are 484-pin Fine Ball Grid Array-type (FBGA). What that means is there are 484 little balls of solder underneath it. Soldering these things is difficult because all 484 balls of solder need to melt at once. Otherwise the chip will come down crooked or you will get a bad solder joint.

I've tried soldering 484-FBGA before myself with a toaster oven. I followed this guide:
http://www.instructables.com/id/Toaster-Oven-Reflow-Soldering-BGA/
It's tricky because you have to put the right amount of flux down, plus get an even temperature everywhere. For me, it looked good but I had some bad solder joints. So although it will be possible to upgrade from a 1-chip board to a 2-chip board, I sure wouldn't try it unless you have lots of experience.

3. I'm gonna have to say no again. Sorry!

enmaku

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Quote from: newMeat1 on August 22, 2011, 10:16:22 AM

Fritzing Fab- that's a nice service, but it looks like they only make 2 layer boards :/

Ah, didn't notice that. Also I honestly forgot you'd mentioned you're working with 4-layer boards, guess that would drive the cost of fabrication up a bit Tongue

newMeat1

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Fritzing Fab- that's a nice service, but it looks like they only make 2 layer boards :/

enmaku

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Quote from: newMeat1 on August 21, 2011, 12:32:08 AM

if we only make 5, each PCB costs about $60. If we make 70, each PCB costs less than $10

Have you tried Fritzing Fab? Just going from their examples it seems like they'd be cheaper. Not sure if you can have them leave the white paper off since you're working with SMD stuff (or if they leave a hole in it for the component?) but I thought I'd put it out there.

sirky

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I wonder what the best way to mount a bunch of these would be. Surely just laying them somewhere cannot be most efficient.

What are the physical dimensions with the heat sink on?

newMeat1

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Well just because we expect a nice price drop from gen 1 to gen 2, don't expect any miracles after that! Gen 1 had some obvious problems, but Gen 2 should take the Spartan 6 just about as far as it will go.

I bet we probably won't do a Gen 3 until the Virtex-7 comes out, but who knows when that will be?

Keninishna

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Nice looks like your down to 3$/mh I'm starting to get temped Grin

I think I'll probably wait another gen.

fizzisist

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SolomonVR, leaving the heat sink off the board is probably a good idea, especially for shipping. Maybe Cablesaurus can offer some alongside the boards as an "accessory," although some kind of heat sink is definitely required. When you say additional power connector, what type did you have in mind? The Molex type is ideal, because we can be pretty sure that someone won't connect a different voltage than required, or reverse the polarity. We can consider adding a second connector (or at least the footprint for you to solder it on yourself) if you have a good option.

As for the software, fpgaminer is in charge of the development. I'm sure he'd appreciate help if you're offering!

newMeat1

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ElectricMucus- those are hard questions. I'm gonna have to consult with the team before i answer them.

SolomonVR- the next batch (coming out in 3 weeks) will be much cheaper. See 2 posts above yours. Yes, there will be mounting holes on the next batch (it was planned for the first batch but things got confused...). Yes, we eliminated the Programmer for the next batch. About the rest of your comment, I'm not sure what to say. Maybe a member of my FPGA team can help me out.

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