Ok to use 6 to 8-pin adapter with a 3080 ti?

harmattan

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I've got an XFX ProSeries XXX 850w PSU that has two 8-pin PCIE connectors and two 6-pin connectors. I have a new KFA2 (Palit/Gainward/Galax) RTX 3080 ti HOF coming that has three 8-pin connectors. Can I use a 6-pin to 8-pin adapter to connect one of my PSU's 6-pin cables to the third 8-pin connector on the card?
 

harmattan

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Great. I was worried, with the additional headroom on this AIB (400w vs. 350w on reference 3080 Tis) the 6-pin cables which are, as I understand, only rated for 75w may not be enough. I was thinking an adapter that connects dual 6-pin molex to a single 8-pin may be safer, but I don't think these exist.
 

Zepher

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harmattan

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they exist
https://www.amazon.com/PCIe-Adapter-Power-Cable-Graphics/dp/B085VQ94YJ
this is an example, I can't vouch for the quality of this brand
Those strangely look out of stock everywhere, although there are plenty of single 6-pin to dual 8-pin which seems... not a good idea. Luckily, I was able to dig one up from my bottomless box of connector cables (likely came with one of my past cards and I'd tossed aside). My new 3080 ti may come with one in the box, in any case, but they never list this in specs.
 

OFaceSIG

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I would say as long as you go from two six to one eight, has the linked unit shows, and the cables are of the correct gauge you should be fine.. I would never used a single six to a single 8 adapter as they do exist but you'd be obviously exceeding the 6 pin spec.
 

cdabc123

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Great. I was worried, with the additional headroom on this AIB (400w vs. 350w on reference 3080 Tis) the 6-pin cables which are, as I understand, only rated for 75w may not be enough. I was thinking an adapter that connects dual 6-pin molex to a single 8-pin may be safer, but I don't think these exist.
A 6 pin can pull upwards of 300w. It is tied to the 12v rail in the same way a 8pin would (an 8 pin only has 3 12v wires as well) they just like to provide the option for the hof cards as some people push some generations of those way beyond stock. No reason to worry about the limitation of any of those connectors you wont be pulling too much power.
 

harmattan

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A 6 pin can pull upwards of 300w. It is tied to the 12v rail in the same way a 8pin would (an 8 pin only has 3 12v wires as well) they just like to provide the option for the hof cards as some people push some generations of those way beyond stock. No reason to worry about the limitation of any of those connectors you wont be pulling too much power.
Excellent. I was actually dithering on getting the HoF card. It's supposed to be one of the better build and heftier cards, but has a higher TDP and voltages (allowing it to overclock further past its already high clocks). At least my CPU is well undervolted so I don't think it will cause my PSU any issues.
 

Tsumi

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If your 6-pin cable has 3 12v lines and 3 ground lines, I wouldn't worry about using a single 6 to 8 pin adapter. The 8-pin cables have 3 12v lines and 5 ground lines, and those 2 extra ground lines sure aren't helping the 12v lines carry any extra load. If your 6 pin has only 2 12v lines (rare on quality PSUs), I would be more hesitant about using a single 6 to 8 pin adapter.

Alternatively, if you have a spare EPS cable, you can get an 8-pin EPS to 8-pin PCI-E adapter. Google says you should have 2 EPS connectors. Google also does say all of your PCI-E connectors should be 6+2 pin.
 

Mchart

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The best answer is right above. If you're inpatient just take a paperclip to ground the sense, which is all an 8-pin cable is effectively doing anyways.
 

harmattan

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If your 6-pin cable has 3 12v lines and 3 ground lines, I wouldn't worry about using a single 6 to 8 pin adapter. The 8-pin cables have 3 12v lines and 5 ground lines, and those 2 extra ground lines sure aren't helping the 12v lines carry any extra load. If your 6 pin has only 2 12v lines (rare on quality PSUs), I would be more hesitant about using a single 6 to 8 pin adapter.

Alternatively, if you have a spare EPS cable, you can get an 8-pin EPS to 8-pin PCI-E adapter. Google says you should have 2 EPS connectors. Google also does say all of your PCI-E connectors should be 6+2 pin.
It's actually the XFX PRO850w Core Edition Wired, just took my sound card out to see the exact model (this one). I had bought it all the way back in 2012 as a replacement PSU, but then stuck with another unit. It was sitting in an unopened box until 2 years ago when I re-built my machine and it's been working great across multiple components. It looks like it's got a single +12v 70A rail to which I assume all of the PCIE cables are connected.
 

WilyKit

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Both 6 and 8 pins have the same amount of wires delivering power. The difference is 2 extra ground wires on the 8 pin. Those 2 ground wires are basically just telling the card "yes, the 3 hot wires are robust enough to handle the load" where has the 6 pin don't have those two extra ground wires to say "yes the 3 hot wires are robust enough to handle the load"
 

harmattan

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Running fine with the dual 6 to 8 pin adapter, super stable. I'm able to overclock to a stable 1950mhz core which is impressive for a 3080 ti from what I've read. My 5800x is underclocks aggressively so hoping I won't have any issues.
 

Tsumi

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Both 6 and 8 pins have the same amount of wires delivering power. The difference is 2 extra ground wires on the 8 pin. Those 2 ground wires are basically just telling the card "yes, the 3 hot wires are robust enough to handle the load" where has the 6 pin don't have those two extra ground wires to say "yes the 3 hot wires are robust enough to handle the load"

That's technically incorrect. The original 6-pin PCI-E spec called for 2 12v, 2 ground, and 1 sense; sense is not considered a power carrying ground. It is rated for 75 watts. The 8-pin PCI-E adds a 12v, ground, and sense and ups the rating to 150 watts. In a typical quality PSU, the components used in an 8-pin PCI-E cable are good to 500 or 600 watts.
 
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