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Title: PCIE power splitter 6pin -> 2x8pin Post by: asbator on September 12, 2017, 08:08:08 AM Running 300W on 75W designed connector seems like terrible idea.
But those connectors are very popular, people are buying them and giving top marks. I have 1300 EVGA Supernova running just 6 cards using 780W. I'm thinking about expanding the rig, but PSU has connectors for "just" 6 GPUS. How to connect safely 2 more GPUs? I want to be 100% sure it's safe, safety is top priority after all, don't want to burn house trying to earn couple of bucks. Title: Re: PCIE power splitter 6pin -> 2x8pin Post by: asbator on September 12, 2017, 09:48:01 AM Made some research. Double GPU cards like R9 295x2 are pulling up to 300W from 8pins wire, that has 3 circuits in it.
This gives 100W per circuit. Corsair AX1200i can output up to even 480W on 8pins wire (40A) -> what gives even 160W per circuit. Problem is i have different PSU, which has only 8+6 pins wires, like engeneers wanted to say that 300W is really max PSU can give on 3 circuits, though only 225W is safe. So 8pin to 2x 8pin splitter seems reasonable. But why market is flooded with 6pins -> 2x 8pins. (Why even bothering doing them?) Title: Re: PCIE power splitter 6pin -> 2x8pin Post by: crocozino on September 12, 2017, 09:57:03 AM in fact you can use your 6 pin on 8 pin cards, the 2 missing pins is just ground you may just shorten them
http://www.goldfries.com/images/computing/6to8pinpcie/6to8pinpcie01.jpg like here for 1070 I think you should be pretty fine with it Title: Re: PCIE power splitter 6pin -> 2x8pin Post by: asbator on September 12, 2017, 11:05:31 AM in fact you can use your 6 pin on 8 pin cards, the 2 missing pins is just ground you may just shorten them http://www.goldfries.com/images/computing/6to8pinpcie/6to8pinpcie01.jpg like here for 1070 I think you should be pretty fine with it There is sense on 4th and ground on 8th. I think it's still not good since temperature depends on amperage not voltage. And amperage is same on +12 and ground line. So this missing ground line is needed there. Maybe im wrong? I had physics class over 10 years ago... Title: Re: PCIE power splitter 6pin -> 2x8pin Post by: QuintLeo on September 12, 2017, 08:09:24 PM Running 300W on 75W designed connector seems like terrible idea. The connector ITSELF is rated for 288 watts - but the WIRING to it out of most power supplies is commonly NOT rated more than perhaps 150-200. Splitting a 6-pin to a pair of 8-pins is A VERY VERY BAD IDEA. The connectors on the EVGA G2 1300 POWER SUPPLY aren't wired the same as PCI-E connections - I'm pretty sure they are using 4 pins each for +12v and ground, so those should be able to handle 350 watts or so - given that the PCI-E spec for an 8-pin connector limits it to 150 watts, you should be able to safely run an EVGA-type dual-cable from EACH of those connections on the power supply as long as you don't exceed it's total power capacity. The PCI-E spec is VERY VERY conservative on avoiding overload on the power connectors. Don't confuse THAT spec with what the connector ITSELF is actually rated at. |