Klondike - 16 chip ASIC Open Source Board - Preliminary

[turtle83]

Stupid question: Can i use the 16 chip board with fewer than 16 chips on it? Or it needs all 16 in place to be able to work?

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[BkkCoins]

I've had quite a few PMs and people demonstrating interest. Some are helping to fund prototype boards. Thank You.

Since I won't have to do it all myself I've decided that the 2 layer board is history and I'll be moving directly to working only on the 4 layer board. In 100+ qty the cost difference is not worth the hassle, and the 4 layers will result in an overall better board. It does raise the ante a bit for people who want to make their own boards, as they'll need to commit more up front, but I think later I'll be able to offer cheap enough boards for those who only need a few.

Stupid question: Can i use the 16 chip board with fewer than 16 chips on it? Or it needs all 16 in place to be able to work?

At this time I believe you'll be able to use from 1 - 16 chips per board. Also, it's possible to populate only one 1.2V regulator and related parts enabling a lower parts cost when < 8 chips are present. The only thing that would prevent this is if the Avalon chip specs are released and there is some reason that only 10 chips will work. Assuming the chips can work individually (which I'm pretty confident about), then the on board PIC will take care of whatever chips are present.

[loshia]

Since I won't have to do it all myself I've decided that the 2 layer board is history and I'll be moving directly to working only on the 4 layer board. In 100+ qty the cost difference is not worth the hassle, and the 4 layers will result in an overall better board. It does raise the ante a bit for people who want to make their own boards, as they'll need to commit more up front, but I think later I'll be able to offer cheap enough boards for those who only need a few.

1+ for four layer PCB!

[loshia]

BkkCoins,

Please comment my Power thoughts. I am armature with hardware. So please excuse me if there is something stupid posted

According to Avalon:

Chip power efficienty: 6.6W/GHs @ 1.15 V

When chip is clocked at 300 my Avalon is making 71.5 Gh stable all the time

I am not an expert but simple math as I see it is:  71.5/240(chips)x7W each(about 8% on top over clocked)x16Chips as planned = 33.33W/1.2V/2 (each group of 8 chips) = 13.90A

As you stated:

I only pull 12A from each IR3895 keeping it in the more efficient operating area and not pushing it's heat dissipation.

So will be 12A enough to over clock chips at 300?
PS:
Other way around

Module power consumption: 149W @ 20GHs / 164W@ 22GHs

164/80*16/1.2/2=13.67 Amps clocked at 275 (or 285 i do not remember exact number)
However it would be more when clocked at 300

[BkkCoins]

BkkCoins,
I am not an expert but simple math as I see it is:  71.5/240(chips)x7W each(about 8% on top over clocked)x16Chips as planned = 33.33W/1.2V/2 (each group of 8 chips) = 13.90A

So will be 12A enough to over clock chips at 300?

I'm curious if you've measured actual at wall power use when over-clocking? Is 8% based on that or on the 71.5 / 66 ratio. It may not be a linear increase. It would be useful to know what "at the wall" actual power use is.

The IR3895 is rated at 16A and the inductor is rated at 18A. I feel relatively safe they'll be ok at 14A but the efficiency will take a bit of a hit - about 1-2% more loss. Lowering the voltage from 1.2 to 1.15 is likely beneficial in reducing power use and heat. The voltage is determined by a resistor pair on the buck regulator and it supports as low as 1.0V. It's quite feasible during testing I'll be able to determine that a under-volted core supply is workable. It seems like Avalon does this and it's something to look at.

I thought about a programmable resistor to allow software control of core voltage but I'm not sure that's worthwhile. It would depend if there is a suitable product cheap enough. Like an I2C/SPI 8 pin chip or something. I may explore that later if time allows - it would be pretty nice.

[wizzardTim]

I am interested in getting a board. Can you tell me what would be the price approximately?

[Rallye]

I will be following this closely.  I bought 592 chips in the first group buy with the intention of getting 37 of your boards. 

[salty]

I'm watching this thread Put me down for 8 boards please...


Edit: Donated too, at least I think I did, my Bitcoin-QT crashed while typing my passphrase and it's re-indexing now grrrrrrr.... Of course this donation is a contribution to your efforts, not an expectation of entitlement to free boards or anything.

[BkkCoins]

I am interested in getting a board. Can you tell me what would be the price approximately?

I can only give a vague idea right now. It could change when Avalon specs come out. I have done a detailed parts list and pricing but much also depends on what economies can be reached when ordering parts. Here is a rough breakdown:

Board qty. 30 - $5 each. or qty. 100 - $2.70 each.

Parts qty. 10-25  $25 each. may be able to get this down to $20 in 100+ qty.
This is based on Mouser USA. Maybe I can source more stuff in Asia.
(there's almost 250 friggin capacitors on there!)

Heat sink, no idea but they seem costly online, like $12.
When I have time I'll be looking for something cheaper. I've seen $3-5 ones and think in qty this is doable. I have an old socket 470 cpu heat sink that's almost right.

Assembly ? Not sure what to charge but it would be something like $10-20 each.
You supply your own case, fan, usb cable, power splitters if needed.

So you could be looking at between $60 - $80 or so. Much depends on what qty I can buy and how many get ordered and whether I farm out assembly to a factory in Bkk. Let's wait until I have a working board.

[samurai1200]

If the design is proven, I'd be willing to do a manufacturing run here in the USA, or done elsewhere and shipped here, then distributed by me. I know there's lots of trust issues surrounding this, but we'll work that out once BKK gets closer to completing his design & firmware/other software. I'll be following this thread closely.

[mgio]

This seems great! I'm in the process of getting some Avalon chips now so I'm definitely interested. I'll send you a donation when I get home today.

[nebulus]

Watching...

[tosku]

About the heatsink. If the board is 10x10cm, how does a socket 478 heatsink fit? It's only 3.5 cm x 3.5 cm. Would the board be using four heatsinks, one for each group of four Avalon chips? Or will there be a large heat-spreader on the reverse side of the board, and a single heatsink in the center?

Anyway, CPU heatsinks are cheap. I found the socket 478 variety for less than $3 including a fan and shipping from China, if you buy them in a sufficiently large quantity. Other kinds of heatsinks for newer sockets can be had as cheap. And pretty much any CPU heatsink can cool off 35W without any problems.

[zif33rs]

Subbed. Watching with interest.
 

[loshia]

BkkCoins,
I am not an expert but simple math as I see it is:  71.5/240(chips)x7W each(about 8% on top over clocked)x16Chips as planned = 33.33W/1.2V/2 (each group of 8 chips) = 13.90A

So will be 12A enough to over clock chips at 300?

I'm curious if you've measured actual at wall power use when over-clocking? Is 8% based on that or on the 71.5 / 66 ratio. It may not be a linear increase. It would be useful to know what "at the wall" actual power use is.

The IR3895 is rated at 16A and the inductor is rated at 18A. I feel relatively safe they'll be ok at 14A but the efficiency will take a bit of a hit - about 1-2% more loss. Lowering the voltage from 1.2 to 1.15 is likely beneficial in reducing power use and heat. The voltage is determined by a resistor pair on the buck regulator and it supports as low as 1.0V. It's quite feasible during testing I'll be able to determine that a under-volted core supply is workable. It seems like Avalon does this and it's something to look at.

I thought about a programmable resistor to allow software control of core voltage but I'm not sure that's worthwhile. It would depend if there is a suitable product cheap enough. Like an I2C/SPI 8 pin chip or something. I may explore that later if time allows - it would be pretty nice.

I have not measured power yet. I do completely agree that we have to pay the efficiency cost when we do overclock. What woried me that other elemnts will not allow more than 12A but this turns to be false a.larm
Thank you for your update

[bassclef]

About the heatsink. If the board is 10x10cm, how does a socket 478 heatsink fit? It's only 3.5 cm x 3.5 cm. Would the board be using four heatsinks, one for each group of four Avalon chips? Or will there be a large heat-spreader on the reverse side of the board, and a single heatsink in the center?

Anyway, CPU heatsinks are cheap. I found the socket 478 variety for less than $3 including a fan and shipping from China, if you buy them in a sufficiently large quantity. Other kinds of heatsinks for newer sockets can be had as cheap. And pretty much any CPU heatsink can cool off 35W without any problems.

Bkk correct me if I'm wrong but the sinks would simply be mounted to the back of the pcb, Avalon style.

A quick look at heatsinkusa.com shows a ~4x4" sink costing around $5, give or take a bit  depending on how high the fins need to be.

[BkkCoins]

About the heatsink. If the board is 10x10cm, how does a socket 478 heatsink fit? It's only 3.5 cm x 3.5 cm. Would the board be using four heatsinks, one for each group of four Avalon chips? Or will there be a large heat-spreader on the reverse side of the board, and a single heatsink in the center?

Anyway, CPU heatsinks are cheap. I found the socket 478 variety for less than $3 including a fan and shipping from China, if you buy them in a sufficiently large quantity. Other kinds of heatsinks for newer sockets can be had as cheap. And pretty much any CPU heatsink can cool off 35W without any problems.

No the old socket 478 heat sinks are huge and can handle more like 90W as the old P4 CPUs were major power gluttons. The one I have here is 10cm long and about roughly 6 or 7cm wide. It has a big fan that clips on top with plastic side arms.

Like this, $8 brand new on Amazon.
http://www.amazon.com/Intel-Copper-Core-Socket-3-40GHz/dp/B000F6UW5W

But they're cheaper on ebay and there are after market ones that aren't as tall.

I also have a 1" high full-copper one from a 1U server I had 8-9 years ago. Must be worth a lot now. Anyway it's not perfectly the right width but length is right. I could probably take 2 of them and cut them with my angle grinder and put them together to make a perfect fit.

I have some sheet Aluminum here that I used to make ceiling light enclosures. I may cut some of that up and bend it into a custom heat sink for testing. If it works well I could make a whole batch of them. Materials cost would be < $1 each but there would be labour to cut and bend  and assemble. Just an easy DIY option. Would need thermal compound too.

I'm sure something can be worked out for a reasonable cost.

[BkkCoins]

About the heatsink. If the board is 10x10cm, how does a socket 478 heatsink fit? It's only 3.5 cm x 3.5 cm. Would the board be using four heatsinks, one for each group of four Avalon chips? Or will there be a large heat-spreader on the reverse side of the board, and a single heatsink in the center?

Anyway, CPU heatsinks are cheap. I found the socket 478 variety for less than $3 including a fan and shipping from China, if you buy them in a sufficiently large quantity. Other kinds of heatsinks for newer sockets can be had as cheap. And pretty much any CPU heatsink can cool off 35W without any problems.

Bkk correct me if I'm wrong but the sinks would simply be mounted to the back of the pcb, Avalon style.

A quick look at heatsinkusa.com shows a ~4x4" sink costing around $5, give or take a bit  depending on how high the fins need to be.

Yes, that's right 4"x4", drill four holes and bolt on to back. I'll have an open copper pour on back for tight mating with thermal compound. The entire surface will be GND with no traces.

I looked on heatsinkusa and could only see a $12.35 option for 4" wide cut to 4" length. I guess I didn't find the right one. Can you give me a link to the $5 one? I'd like to see and if it's right then I'll just tell people they could order those, though I think even cheaper options could turn up.

Maybe someone can send me one to test and confirm later on when I have boards.

[bassclef]

I looked on heatsinkusa and could only see a $12.35 option for 4" wide cut to 4" length. I guess I didn't find the right one. Can you give me a link to the $5 one? I'd like to see and if it's right then I'll just tell people they could order those, though I think even cheaper options could turn up.

I see they have a 4" wide option with 2" high fins for $12. Maybe that is large if we want to stack them close together.

They also have 3.5 and 4.2" inch sizes with .75" high fins for about $4 and $5 respectively. If 3.5x4" is big enough, $4.36 is pretty cheap.

[TheJuice]

love it. Definitely would be in.