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Other => CPU/GPU Bitcoin mining hardware => Topic started by: mb300sd on August 31, 2011, 06:44:50 AM



Title: Board with most PCIe slots. x1, x4, x8 or x16.
Post by: mb300sd on August 31, 2011, 06:44:50 AM
Does anyone know what the board with the absolute most PCIe slots of any width is? The only spec I can find on newegg is the number of x16 slots.

Also, Does anyone make a splitter that can turn a x16 slot into 16 x1 slots? It should be possible based on my knowledge of how PCIe lanes work and looking at the pinouts.. I may cut up a couple extenders and resolder them to see what happens.


Title: Re: Board with most PCIe slots. x1, x4, x8 or x16.
Post by: KarlSpaat on August 31, 2011, 07:19:44 AM
MSI BigBang Marshal has 8 PCIe16 slots. I dont know if there are any cheaper boards with 8 slots.


Title: Re: Board with most PCIe slots. x1, x4, x8 or x16.
Post by: SuperTramp on August 31, 2011, 08:27:45 AM
Here is an AMD AM3+ board with 6 PCIe slots: http://www.newegg.com/Product/Product.aspx?Item=N82E16813128508


I actually have this one running right now with 4x 5830s: http://www.newegg.com/Product/Product.aspx?Item=N82E16813128509

It has 6 PCIe slots as well: PCI Express 2.0 x16:  5 (x16, x16, x8, x4, x4)
                                     PCI Express x1:         1



-ST


Title: Re: Board with most PCIe slots. x1, x4, x8 or x16.
Post by: cicada on August 31, 2011, 01:56:28 PM
Also, Does anyone make a splitter that can turn a x16 slot into 16 x1 slots? It should be possible based on my knowledge of how PCIe lanes work and looking at the pinouts.. I may cut up a couple extenders and resolder them to see what happens.

There are expansion boards that can do this, as well as a couple of external PCIe enclosures, however they're all rather expensive.

Unfortunately it's not a plug-and-go matter of splicing in new connectors and sharing the bandwidth, it requires some logic ICs to handle multiplexing the signals to all the connected devices properly.

Most of that kind of thing is aimed at the high-end server crowd right now as the average user doesn't need or want to split out a 16x slot.  Someone producing such a thing cheaply would go over fairly well in this crowd.



Title: Re: Board with most PCIe slots. x1, x4, x8 or x16.
Post by: mb300sd on August 31, 2011, 02:48:43 PM
Also, Does anyone make a splitter that can turn a x16 slot into 16 x1 slots? It should be possible based on my knowledge of how PCIe lanes work and looking at the pinouts.. I may cut up a couple extenders and resolder them to see what happens.

There are expansion boards that can do this, as well as a couple of external PCIe enclosures, however they're all rather expensive.

Unfortunately it's not a plug-and-go matter of splicing in new connectors and sharing the bandwidth, it requires some logic ICs to handle multiplexing the signals to all the connected devices properly.

Most of that kind of thing is aimed at the high-end server crowd right now as the average user doesn't need or want to split out a 16x slot.  Someone producing such a thing cheaply would go over fairly well in this crowd.



You're right, I'm studying the pinouts a bit more and it looks like REFCLK and WAKE are the ones that cause the trouble. SMBus is easy to split and JTAG is optional... Back to researching..maybe I can find a cheap IC and start producing these.


Title: Re: Board with most PCIe slots. x1, x4, x8 or x16.
Post by: cicada on August 31, 2011, 03:12:30 PM
You're right, I'm studying the pinouts a bit more and it looks like REFCLK and WAKE are the ones that cause the trouble. SMBus is easy to split and JTAG is optional... Back to researching..maybe I can find a cheap IC and start producing these.

Don't underestimate the bandwidth involved here, even though it's relatively low for mining compared to gaming.  Up to 64Gbit for a 16x slot according to PCIe 2.0 specs.  In reality the GPUs can't throw a stone anywhere near that number, but it's something to be aware of when choosing your IC.   I don't know much about how the bandwidth is split between lanes, perhaps it's possible to bypass the IC for these data channels and let the motherboard handle it.

I'd assume you'd have to re-broadcast the clock signals to the connected devices, I think you're going to run into some latency problems here that will either be a major roadblock, or contribute to a lot of invalid hashes at least.

Note that i'm not trying to be a pessimist, just thinking this isn't going to be an easy task.


Title: Re: Board with most PCIe slots. x1, x4, x8 or x16.
Post by: trippp on August 31, 2011, 06:51:26 PM
Back to researching..maybe I can find a cheap IC and start producing these.

I think you should let this discussion grow to a thread of it's own. I bet a lot of miners would be willing to pay hundreds dollars for a device with extra PCIe slots.