GTX 980 Power cable/SLI

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Kjays

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Sep 27, 2013
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Howdy

Got a new GTX 980, which requires 2x 6pin connections to power it.
My PSU came with an 8pin to dual 6+2 pin cable, which is split at the end.

Is it fine to use this to power the card, or should i be using two separate cables.

One final question, is 650W too little to SLI this card? i have a Seasonic X series PSU which i know is quality, but as far as raw wattage is concerned, is it enough?
 
Solution
geofelt
It matters not how you use the psu cables. I would go ahead and use the single cable with the two 6+2 plugs. Just leave the +2 hanging. The psu is perfectly capable of powering both and your cabling will be simpler.

Normally, one would want about 750w for sli GTX980.
But, your Seasonic x is an exceptionally good psu with reserve power.
They supply enough leads to handle 4 8 pin connectors so I think sli GTX980 would work fine.
If the time comes, for sli, go ahead and try it. If there is insufficient power, the psu has good protective circuitry so no harm will come.
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geofelt

geofelt

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It matters not how you use the psu cables. I would go ahead and use the single cable with the two 6+2 plugs. Just leave the +2 hanging. The psu is perfectly capable of powering both and your cabling will be simpler.

Normally, one would want about 750w for sli GTX980.
But, your Seasonic x is an exceptionally good psu with reserve power.
They supply enough leads to handle 4 8 pin connectors so I think sli GTX980 would work fine.
If the time comes, for sli, go ahead and try it. If there is insufficient power, the psu has good protective circuitry so no harm will come.
 
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carlosriosness

carlosriosness

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i have a hx850i with (2) gtx 980ti cards. i have the same question, but seem to get different answers.

some say its ok to run 1 cable to each card (since 1 cable has dual 6+2 tips)

others say each power port on a gpu should get its own cable, otherwise the cables will melt. (requiring me to run 4 power cables)

is that an old urban legend or does that still happen? would a newer PSU like the hx850i be smart enough to reduce power before any melting took place? or are cables better rated now a days?
 
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geofelt

geofelt

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Pure FUD.
A PSU is designed to properly power all of the leads it has simultaneously.
And...
The HX is a tier 2 unit on this list.
https://community.newegg.com/eggxpert/computer_hardware/f/135081/t/45344.aspx?Redirected=true

Not to worry.
 
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carlosriosness

carlosriosness

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"A PSU is designed to properly power all of the leads it has simultaneously." thats exactly what i think a PSU is designed to do.

i mean why would they ship 3 sets of these dual 6+2 cables if the system couldnt handle it?
 
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geofelt

geofelt

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You know, I need to amend my statement a bit to add "within the limits of the total psu capability"
A 6+2 pin lead can each potentially supply 150w.
6 of them could total 900w and added to the rest of the load would exceed the normal 850w capability.
A quality unit like the HX can probably exceed the 850w claimed, but you get the idea.
A Normal GTX980ti needs a 6 and a 8 pin lead plus the pcie slot.
That is 75w ,150w, 75w respectively for a maximum total of 300w per card.
Two of them still leaves 150w which is sufficient for any normal cpu plus a few drives.
 
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king3pj

king3pj

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I have another similar question. My EVGA G2 850W has the same cables as this with each PCIe cable having a split with two 6+2 pin cables at the end.

I have SLI 970s that each require two 6 pin cables. Instead of using 4 separate PCIe cables I took advantage of the dual outputs on these cables and switched down to 2 PCIe cables.

When I did this it was much easier for my cable management to plug one dual cable into the left power ports on both of my 970s and the other power cable into the right ports on both of my 970s. Instead of using my dual cables to plug in both ports on one card each cable is plugged into both cards.

Thinking about it later I'm not sure if this is okay. Is the power supply smart enough to regulate power for two separate cards on the same cable? Are both of my SLI 970s getting the right amount of power even in games where only one card is being used?

Since doing this change I have only played a couple hours of Heroes of the Storm but this is not a SLI game. I haven't had a chance to see if everything is still good when both cards are under load yet.
 
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king3pj

king3pj

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That is good to hear. My airflow should be much better now than it was before and I really didn't want to switch it back.
 
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