Bitcoin Forum

I have run across this listing, and I'm wondering if it will function properly mining with a lot of cards, using the BAMT linux disto, or any other linux setup.

Are there any limits to the number of GPUs per system? Will running 4 pci-e 1x cards per slot x 5-6 slots overload the pci-e lanes?

http://www.ebay.com/itm/PCI-e-express-1X-to-4port-1X-16X-multiplier-riser-card-cable-4-diy-bitcoin-miner-/321248295196?pt=LH_DefaultDomain_0&hash=item4acbe3f91c

I was sticking to 5 gpus per system, on the cheap base systems I have (gd45 mobos, 8gb ram) but the idea of turning that into 20-25 gpus per base unit would be very entertaining! (Not that I could find enough GPUs to fill it at this time)

for $80 you can get a whole new motherboard with 4+ slots.

Yeah, but motherboard, plus ram, plus cpu, plus thumbdrive, plus setting up and maintaining each system becomes a pain as the systems grow. If switching from risers to these lets me 4x the number of cards per system, that would be amazing.

Also, each mobo requires an atx connection so more power supplies or less organized cases :)

Hi RickJamesBTC,

You ever found that answer to the number of GPUs per system? Also, what are your thoughts about powering a 10 GPUs?

Nobody seems to have tried these, so who knows.
As for power, if all you need is LOTS of +12, it is easy to do. I have three phase power personally, so I could buy big surplus 4kw-6kw 12v power supplies and run the cards directly from them. Building them as individual systems has led me to just use pc power supplies, but being able to run a large increase in cards with far less atx requirements would be good motivation to try that.

It would definitely be wonderful if 20-25 gpus could work in a single system.
However, this is not easy at all. There are various limits of gpu numbers coming from bios, OS, drivers, power delivery...
Check this thread for reference:
https://bitcointalk.org/index.php?topic=64450.0

Oh well, looks like amd can't be bothered.
Well if they ever release a driver package that can handle many gpus, I hope these are still available.

What's the max number of cards for nVidia drivers? With the hash/power ratio of Maxwell, it'd be interesting to try this if nVidia allows > 8.

That does not count the hard coded to WinBlows 9 screen max.  I mean 9 monitors so dual head cards can count as 2 screens.  I'm not sure what ( if any ) Linux distros may have as a limit and the original eBay actually can only do 2 cards per that adapter.  The white for one type and the black for PCIx16 cut down to the x1 speed ( read the fine print people!! ) so you would need 2x of them per slot to only doubble your GPUs and most likely 1 dummy plug on all but what you actually look at to get up to 8 ( best guess guestimate ) cards per average 4 pci/pcix16 mobo out there.  Still... good luck actually finding that many that will play nice together.

in windows everything works OK

I will test it at mining later

http://omniserver.pl/4ddd5/2014/multi%20pcie/1.JPG
http://omniserver.pl/4ddd5/2014/multi%20pcie/2.JPG
http://omniserver.pl/4ddd5/2014/multi%20pcie/3.JPG

I wonder how R9 290x Cards will hold up since they use much more power..

Also what would happen if you fill each slot with 4 x PCIE multiplier

over 20 GPU's Then make them all R9 290x and I just dont see it happening something will pop lol Id lover to see it go though 

I am using usb risers so power of pci-e doesnt matter for me.

Anyway, with usb risers and without molex, multiplier doesnt work.
So you have to plug molex connector.

Wow thats alot of wiring for 1x4 gpus. I'd want to see a pic of setup of this with 7-8x4 gpu motherboards, hah!

With the pics, i admit my other statement is completly WRONG.  The ' other ' multipliers I could find ( some on eBay, the actual ICs on TI.com ) were mostly 2x with an option of what speed and thus a colour difference in slots IF it had 4 slots.  Just looking at the pic of the actual card, there are more pins on that one multiplyer IC ( over 40ish in quad flat pack ) and it definitly looks like it actually talks to each slot individually.  I'd love to find out the hard coded limit ( if any ) for GPUs with that kind of thing.

dont have any proof for now but, I make rig today  - 4x 270x  direclty from motherboard (asrock btc) and  3x 280x (on multiplier).Everything works fine (speeds 600/720/720khash @ 280x and 450each from 270x) this 600khash thing is normal for me (even without multiplier one card is slower sometimes)


ghetto mounitng and bad nokia e70 pic (also I have bad light in mining room)

http://omniserver.pl/4ddd5/2014/multi%20pcie/4.jpg

cool, thanks for the info!

OK its done

I think hashrates will be the same as plug directly to motherboard.

On 3x 280x i get 590/690/690 (I hate 280x personally) sometimes everything work ok 700-720 each card, sometimes one get slower hashrate (doesnt matter multiplier or motherboard)- I cant explain that

anyway
I change mining on keccak SHA-3 and now everything the same.

Later I will try to put 4x 270 on multiplier and 3x 280x on mobo.

http://omniserver.pl/4ddd5/2014/multi%20pcie/keccak.png