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Can I run 2 GPUs from one PCI-E cable?

by Africsnail / March 24, 2018 4:19 PM PDT

Hello I have the Corsair RM650 PSU and I got cables which are split in two ends (6+2 pins). Can I just use one cable to power my GTX 1070 and RX 570 at once?
Thank you.

Post was last edited on March 24, 2018 4:20 PM PDT

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All Answers

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Your choice.
by R. Proffitt Forum moderator / March 24, 2018 4:24 PM PDT

I think I just looked up that PSU and with a single rail at 54A for the +12V this goes to, there isn't much concern about the PSU.

Remember what you do is YOUR CHOICE.

I wouldn't because the GPUs can yank a lot of power and there is some drop on the wire. To avoid this I'd use two connections with some adapter to tap some 4 pin Molex to PCIe power or even the extra SATA power connection to PCIe power.

There's another issue that only you can answer. Does this cable reach to both cards?

Finally there are SCREAMS as folk mix GPUs and want to kill others about how hard to impossible it is to get them playing together.

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After testing
by Africsnail / March 24, 2018 11:20 PM PDT
In reply to: Your choice.

It looks that it is running good with single cable installed. I have one slot between those GPUs so cable can reach both of them. I tested it with mining cryptocurrency to have maximum load on both cards. I only see some performance spikes on the RX, but that may be due to the OC which I'm running on it. I'll now test 2 cables if there is any difference.

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by Africsnail / March 24, 2018 11:40 PM PDT
In reply to: Your choice.

Why would have the cable 2 8 pin connectors if use say that I can use just one of them?

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For cards that use both.
by R. Proffitt Forum moderator / March 25, 2018 8:21 AM PDT
In reply to: Why

There is a current limit per pin and you see this all over the PC. Look at the big power connector on a motherboard. See how many black wires go there? The current carried is more than what a single connection can carry so more connections.

As to my choice, I have my reasons. I deal with so many machines that I err on the side of caution since I don't want a repair job back.

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