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New build --- 8/6 Pin Pci Express power confusion

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July 23, 2010 7:29:03 AM

I've recently been building a new system and it was going swimmingly until it came to power my HD 5850. The powercool PSU I got was advertised as having 6 pin Pcie connectors (Of which the 5850 needs two), however, it came with some wierd hybrid 6+2/8 cables. Essentially one end was an 8 pin, which I presume plugs into the PSU, and the other end can convert to a 6 pin from a 6+2. The question is would supplying a 6 pin socket through an 8 pin power outlet damage the graphics card? :heink: 
a b B Homebuilt system
July 23, 2010 7:41:03 AM

The extra two couldn't be used. Also they're keyed so you can't put the individual ones in wrong. So it should be fine, the only problem I can think of is that maybe the two extra pins would be physically in the way of something on the graphics card itself.
July 23, 2010 7:48:18 AM

Thanks for the reply, but what I'm worried about is how the PSU is supplying the power out of sockets labelled "8 pin pcie". I have two "6 pin pcie" sockets, but as mentioned the cable only splits to give a 6 pin setup at one end, forcing me to use the 8 pin power outputs.
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a c 122 B Homebuilt system
July 23, 2010 11:26:10 AM

mr pi said:
The question is would supplying a 6 pin socket through an 8 pin power outlet damage the graphics card? :heink: 

No. If you look at the 6 and 8 pin PCIe connectors, they both have 3 hot wires (the yellow 12 volt leads). The 2 wires of the "6+2" connectors are both extra ground leads. So either way, you only have 3 wires carrying power into the video card.

Speaking as someone who has been in electronics for more than 40 years (starting as a hobbyist), I just do not see how adding two ground wires is going to double the current carrying capacity of three hot wires.
July 23, 2010 11:27:35 AM

Thanks for the help, gonna go ahead and turn it on now. Guess I was just fretting over frying my shiny new HD 5850 (upgrading from a 8600gt in my old system).
!