Powering 7970 HD cards. Separated cables or single cables?

I just received my new computer.

It has multiple GPUs (XFX 7970 HD). They have two power sockets:

a 8 pin socket and
a 6 pin socket.

Can I power each card with a single power line? My PSU (Corsair RM1000) comes with PCIe cables that feature two 6+2 pin connectors.

Or do I need to use a separate line on each socket?

jgyou

Posted 2014-01-03T21:10:47.893

Reputation: 123

Are you asking if you need both an 8 pin and a 6 pin cable to power it? If so, yes, you do need both. .-. – DanteTheEgregore – 2014-01-03T21:19:25.350

Sorry @DanteThegregore, I might not have been too clear haha! What I'm asking is if I need separated lines coming from the PSU to the card for each of the plugs on the GPU, or if I can use the same cable for both plugs. – jgyou – 2014-01-03T21:21:29.227

Answers

Single power line is enough, there is no reason to use multiple cables for a single video card.

Vladimir Oselsky

Posted 2014-01-03T21:10:47.893

Reputation: 695

I'm just curious as to why they would put 2 different plug on the card in that case.. – jgyou – 2014-01-03T21:31:54.157

1that I can't answer, I don't know enough about physical structure of video cards to know why manufacturers put 2 different slots. It could be related to different components that need to be powered on modern video card. – Vladimir Oselsky – 2014-01-03T21:39:04.723

Apparently you are right, this popped on a old reddit thread: http://i.imgur.com/rYhlBZM.png

– jgyou – 2014-01-03T21:44:49.847

It should work fine. You can split the power connector to the layout that you need.

A lot of power supplies have ratings for each connector type (12v rail, 5v rail, 3.3v rail) for the maximum amps that they can push. I never concerned myself with this until I started to mine Bitcoins and had several USB Dongles daisy chained on a back plate board. The board required a 5v rail with a 30 amp load.

Here is a pic for your PSU (source). If you're splitting off of the 12v rail, you should be fine (which in great likely hood you would be). However, I would be cautious because having a large load on thin wires could catch fire.

enter image description here

kobaltz

Posted 2014-01-03T21:10:47.893

Reputation: 14 361

Thank you! I'm mining scrypt coins with this rig. Do you reckon that 83.3A on the 12V rail and 25A on the 3.3V is enough for 3 of these XDX 7970 HD? – jgyou – 2014-01-04T03:03:22.110