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i have 6 of these Gigabyte R9 270.  They require 2x 6P PCI-E for power
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125491

I was hoping to run them off two 650w that I currently have... until I realized that I don't have enough cables. Furthermore I don't think these PSU were meant to run more than 1 or 2 cards because there aren't enough slots on the back..  GG.

So I guess I will have to order this 1200w LEPA PSU and hope that it has the right cables:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817494011

I can't tell from the picture, but does it have enough cables to power at least 5 of my Gigabyte R9 270s? It says there are 8x 6+2P, It looks like there are only 3 slots to power 3 GPUs, how do I connect the rest?

Do you guys think I should return the Gigabyte's and get these ASUS R9 270 instead? (they only require 1x 6P for power). Or is there no need with this 1200w PSU?
http://www.newegg.com/Product/Product.aspx?Item=N82E16814121823

If possible I would like to avoid the trouble of returning my GPUs and waiting another week.

I guess this is my dilemma, i cant find any single PSU that will support 5-6 cards, this seems like it would be a common issue?

https://ip.bitcointalk.org/?u=http%3A%2F%2Fi1222.photobucket.com%2Falbums%2Fdd492%2FPandaMarketer%2Fpsu-pcie-card-max.png&t=535&c=fx12_3shpb7G7A

You are unlikely to find a PSU that will have PCIe power for more than 4 GPUs; and some flagships will only handle 3.

There are several cheats before you return cards (bear in mind the popularity means that you might wait weeks before you replaced them).  Better to start with the ones you *can* run then change your approach because of a cable.  You can get your fans sorted and tweak your miner in the meantime.

1.  Use y-cables: PCI-e 8 to 2 by 6+2 and PCI-e 6 to 2 by 6 are available on eBay.  There is no magic tying GPUs to PSU cables, as long as you are sensible in distributing the power and observe the PSU rail envelopes you should be fine.

2.  Make up/rearrange your own cables.  *Be aware* that there is no consistent modular PCIe power standard (ie Antec cables will fritz a Corsair and so on)  Can be hairy - but you can pick PCIe power connectors apart using the two jewellers saws trick.

3.  Use multiple PSUs.

Just to be different, I make up a set of bus-bars  8)

Have you got 270 or 270x?  These are pretty lightweight on power - I have several Gigabyte 270x which I have running at 450khash/s each - I liked the overspec cooling

would you be so kind to post a photo, kind  8) ?  i'd like to know how to do this without killing myself to death.

Depends on your spacing and application:

Here is a set I made up for a total immersion pilot trial using very narrow card spacing (all heatsinks removed).  No problem with naked connectors here, but it's asking for trouble to have an uncovered lump of metal on the back of your system capable of supplying 2.5kW.

http://www.flickr.com/photos/55200254@N02/sets/72157639579479323/

The last set I made used high-current cable soldered to one or two pairs (ie two or four PCI-e power connectors) - one insulated bus per one or two cards going back to a 12V PSU.  I'll post a link later.

The thing to realise is that all those yellow and black wires are there because Molex connectors can't take the total current drawn by the GPU - if the standard moved to high-current connecters you could get away with a two pin (+12V, GND) and lose the PCB supply completely.

For fun, identify the GPU:

http://www.flickr.com/photos/55200254@N02/11851052006/in/set-72157635270016798

 ;D

IMPORTANT - if you do this with conventional PSU you have to reverse the process at the PSU, ensuring that you do not common up different rails.  This method is far more suitable for high current single-rail single-voltage supplies.  I am not responsible for you welding your rig to your metal window frame  ::).

thanks; that is an elegant solution to some shortsighted power supply designs.  let us know when you post the PSU -> soldered cable photos!

Done, although the PSU primary connections are obscured.

The rig has a primary ATX 600W (Thermaltake Litepower) running the mobo and one graphics card.  All the other GPUs are and will be fed off the secondary high-current 12V PSU (slaved), including their powered risers.

When the rig is through soak testing and I've decided whether to go 4, 5 or 6 GPUs I will tie up the flapping wires and secure loose items - until then it's functional and portable with a 10A and a 15A mains lead.