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Author Topic: Crazyness Build Time  (Read 3518 times)
sadpandatech
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October 22, 2011, 03:51:55 AM
 #21

  To add to my post before about external connections.  If your only option is to connect with that express card adapter, there is as I stated an expresscard(universal both EC54 and 34) that will connect to USB.
 Since I did not provide a proper link before I hunted one down. Only $15.99 too.. There is a catch though, and that is the express card adapter you use from the vid card cannot be the pcie type. They say it will jsut not detect. That can likely be hacked if the guys making the other adapters have not already thought of that....

  http://www.amtron.com/expresscard/usbexp54b.htm


 
  I have been searching my nuts off for a straight up PCIe to USB converter. They were seen as useless for the most part whne companies were researching external plugs due to the low badnwidth of USB 2.0 (~490Mbs) verse ExCard or custome solution being very close to PCIe.

  But, we know mining uses very little for badnwidth. And, with USB3.0 having much more badnwidth hopefully some of these options can be reconosidered.

  I wonder how hard would it be for the community here to design a board that converted PCIe to USB and in varying numbr of PCIe slots? I know it would add very little in the way of efficiency to existing PC power consumption. But it would be more efficient none the less. Especially on very low power, underclocked laptops....


  Cheers

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It is being worked on by smart people. -DamienBlack
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catfish
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October 22, 2011, 12:02:06 PM
 #22

To be frank, I can't see any demand for it. USB doesn't supply enough power either - PCIe is itself meant to supply up to 75W.

Firewire, however, is a different kettle of fish and I could see Firewire being adapted to daisychain a load of GPUs...

And thinking of other Mac technologies - that Thunderbolt thing is more or less DisplayPort and probably has the bandwidth to support multiple external GPUs. That's probably where the tech is going.



What would be more useful to me as a bitcoin miner would be a PCIe lane splitter. My favourite 'old faithful' logic board, the Gigabyte H61M-D2-B3, isn't the best example because it's ideal for mining with little wastage. It has one x16 slot, and three x1 slots. I use x1 -> x16 extenders exclusively in my mining rigs, so having lots of x1 slots is useful.

However some of my logic boards have multiple x16 slots - for 'crossfire' and whatnot. Now, if a PCIe *slot* is an x16 spec, does this mean it has 16 lanes? And if a PCIe *slot* is x1 spec, it has 1 lane? If so, then there must be some electronic possibility to connect the pins from the x16 slot into 16 separate x1 PCIe lanes, surely?

It'd obviously need powered risers because each *slot* needs to deliver 75W (or the daughterboard that converted the single x16 slot into 16 separate x1 slots could have its own adapter from the PSU).

But if PCIe lanes actually work like this, and having 16 lanes in one slot can be split up into separate slots, then *very* cheap and small logic boards with only ONE PCIe x16 slot could be made into 'ultimate' mining boards.

I'd be willing to pay for this, if it worked. The logic board situation would become trivial - I'd buy those AMD Hudson integrated thingies - cheap as chips - and then plug in the daughterboard for the multiple x1 slots. It could even be designed such that the x1 slots were actually x16 length and spaced apart properly - maybe no connections to the 'end' pins, but it'd allow many GPUs to be plugged into slots without needing extender cables, and mounting the daughterboard solidly would make all these complex mining rig builds unnecessary.

Anyone know enough to tell me that I'm talking rubbish? Even if the x16 slot can only be split into 4 x1 slots, that'd still be a win if the daughterboard was built to accept properly spaced GPUs and had a long enough cable to plug into the logic board's x16 slot - with my Gigabyte board, I'd end up having 7 PCIe x1 slots - four of which wouldn't require extender cables...

Would this be better off in its own thread?

...so I give in to the rhythm, the click click clack
I'm too wasted to fight back...


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DeathAndTaxes
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October 22, 2011, 01:57:32 PM
 #23

Yes and no.

PCIe has a concept of both lanes and ports.  So the Southbridge has those 16 PCIe lanes configured to a single port.  When you see a board that has 2 slots and it can be 1x PCIe16x or 2 PCIe8x it means the PCIe switch inside the southbridge is capable of dynamically configuring the port to lane assignments. 

Just splitting the lanes physically will do no good.  The PCIe switch inside the southbridge won't "know" there should be 3 or 7 more logical ports.

So what you need is a PCIE switch (a chip which can route PCIe lanes to ports) and that would require a custom PCB.

There are existing solutions which provide PCIe expansion but they are way to expensive.  Here is one example:
http://www.magma.com/expressbox16basic.asp
It adds 16 PCIe slots in an external chasis from a single 16x port.  So hypothetically take a MB w/ 4 PCIe 16x slots connect each one to a 16 bay expansion chasis and gain 64 slots for GPUs.

Two problems.  One the chassis and expander is an insane $4500.  Two AMD stupidly limits you to 8 GPU.

Given the 8 GPU limit I have found the easiest, fastest, and most efficient setup is a motherboard with 3x 16x slots spaced two spaces apart and use 3x 5970s for 6 total GPU.  No other method seems to come close to that in terms of cost.
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October 22, 2011, 05:42:50 PM
 #24

Ive been looking into Magma products fir a while now and while I love the companies products, with them you are paying for enclosure and cabling.

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October 22, 2011, 10:33:53 PM
 #25

Ive been looking into Magma products fir a while now and while I love the companies products, with them you are paying for enclosure and cabling.

A couple other companies make bare backplanes.  Price is still astronomical.  Like >$2K for 16 slots and >$1K for 4 slots.  IIRC Magma doesn't manufacture their own bakcplanes. They are just a Value Added Reseller putting OEM parts together with warranty and service.
PatrickHarnett
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October 23, 2011, 06:09:30 AM
 #26

Don't know if it is still current, but I was looking at this last year (different application) and found some Compaq stuff.  4 16x slots for $3.5k from memory - there were cheaper ways to do this, and having boards with 4 GPUs is ok for what I'm playing with.
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October 23, 2011, 12:48:44 PM
 #27

Yes and no.

PCIe has a concept of both lanes and ports.  So the Southbridge has those 16 PCIe lanes configured to a single port.  When you see a board that has 2 slots and it can be 1x PCIe16x or 2 PCIe8x it means the PCIe switch inside the southbridge is capable of dynamically configuring the port to lane assignments. 

Just splitting the lanes physically will do no good.  The PCIe switch inside the southbridge won't "know" there should be 3 or 7 more logical ports.

So what you need is a PCIE switch (a chip which can route PCIe lanes to ports) and that would require a custom PCB.

There are existing solutions which provide PCIe expansion but they are way to expensive.  Here is one example:
http://www.magma.com/expressbox16basic.asp
It adds 16 PCIe slots in an external chasis from a single 16x port.  So hypothetically take a MB w/ 4 PCIe 16x slots connect each one to a 16 bay expansion chasis and gain 64 slots for GPUs.

Two problems.  One the chassis and expander is an insane $4500.  Two AMD stupidly limits you to 8 GPU.

Given the 8 GPU limit I have found the easiest, fastest, and most efficient setup is a motherboard with 3x 16x slots spaced two spaces apart and use 3x 5970s for 6 total GPU.  No other method seems to come close to that in terms of cost.
OK so it's possible, just expensive.

The trouble with *your* solution DAT is that finding 5970 cards has become rather difficult, not to mention rather expensive in hash per £.

The video card vendors, certainly here in the UK, seem to know damn well that bitcoin miners want the 58xx/5970 cards at any cost and are pumping up the prices. The cheapest I've seen for a usable card (over 200 MH/s for me) is £80 for the 5770. At those prices, when the dual-GPU single cards are costing £600 or more, it's almost worth buying two of my favourite Gigabyte 4-slot boards and running 8 of the 5770s (which all reliably clock up to 220 MH/s each - the disadvantage being space, and potentially efficiency.

I must say that I'm surprised at the cost of the 'lane splitter' solutions. Entire logic boards (like my beloved Gigabyte H61M-D2-B3) cost around £55 inc VAT these days. There's a southbridge on there which splits the PCIe bandwidth into one x16 slot and three x1 slots. Hence the chip logic to split PCIe lanes into different configurations can't be *that* expensive, can it?

I've got an Asus logic board which I've given up on - I bought it for its 5 PCIe slots - and three well-spaced x16 slots (it'd be a candidate for your preferred format, since you'd get your three 5970s onto the board with no extender cables required). A feature in its BIOS allows you to split the bandwidth across the physical PCIe slots - you can disable the two x1 slots and give maximum bandwidth (x16, x8, x8) for three GPUs, or you can have two full-fat x16s with the rest disabled, or the 'x1' config I was trying to get to work, where all slots are available at x1 bandwidth.

This board caused me so many problems (trying to get all 5 slots working with GPUs) that I've taken the CPU out and put it in another Gigabyte board - that's four Gigabyte boards I've got now in my farm Smiley They just work.

However, this Asus board suggests that the BIOS can configure which slots get however many PCIe lanes... so if the software and hardware can already split PCIe bandwidth across the available slots, why are these extension systems so damned expensive?

After all, if the solution I want costs thousands, then I can just bite my tongue and order a few of those damn 'extreme gamer' Big Bong boards which already have 7 PCIe slots on the board (and probably waste 50W or so just running the logic board, requiring more powerful PSUs as well, adding to the cost) Sad

...so I give in to the rhythm, the click click clack
I'm too wasted to fight back...


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Brian DeLoach
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October 25, 2011, 12:52:36 AM
 #28

B) No I do not pay for elec, I have a datacenter, I pay a hosting rate

Is this to say you own a datacenter or are just leasing from one? Since you say your not paying for electricity, leasing has got to be much more expensive?

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