Questions on 2x 8pin VGA power connection

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Gorian

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Mar 10, 2013
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I just got a EVGA 980ti Classified graphics card which requires a 2x 8pin power connection. However years ago I got this Thermaltake toughpower 1500w from a friend and I didnt get any pin cables with it.

So my question is Can I use this spliter and if not what do I need to do here?

PSU modular layout
img10.jpg

Spliter
https://www.newegg.com/Product/Product.aspx?Item=N82E16812423175

Edit: To be clear this is a very old PSU getting the original cables is not an an option. But I have no problem buying what ever cables I need.
 
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Hey I looked around a bit and seems like the PSU is ok with up to 250w per PCIe cable and that should be ok with the card drawing 240w. As for the extender I have to assume it's ok with 250w or more otherwise what would it's purpose even be? Also Im seeing people have used this connector for the 280X and similar connectors with similar cards over 200w.

That said I already have two 6pin cables, so Im going to just play it safe and get a pair of 6 to 6+2 extensions.

Thanks for all the info guys.
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n0ns3ns3

n0ns3ns3

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May 25, 2016
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the PSU comes with those cables. so just ask your friend if he happens to have them.
otherwise search ebay/amazon or any other source for original cables.
you can order custom cables, or make them yourself if you have a multimeter and a basic knowledge of how to work with electricity.
980Ti is power hungry card, so don't connect it anywhere.
i'd be comfortable with 8pin to 2x8pin , but that would require at least one cable that you don't have.
another option is 2x6pin to a single 8pin, but then you don't have that much 6pin connectors.
and of course, there is an option of getting decent 550-650w PSU
 
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InvalidError

InvalidError

Titan
Moderator
May 18, 2007
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It doesn't really matter, the 8-pin connector still only has three 12V wires, the connectors themselves are rated for at least 8A (~96W at 12V) per pin and #18 wires in open air chassis can handle ~16A, so a single properly made 6-pin cable with #18 wires and a proper connector on the GPU are technically good enough for ~300W. The high-current variant of MiniFitJr can handle 13A per pin, which would push the connector's power to 156W per 12V-GND pair at 12V.

The only thing the 8-pin connector does is add two ground wires which serve no purpose other than tell the GPU that it should be able to draw at least 150W from the original six pins, which is still only 50% of what they are spec'd for.

Instead of using a 6-to-8 adapter, the better option would be to to use the 6-pin directly and use a 2-pin jumper to short the two extra pins and trick the GPU into thinking it is connected to an 8-pin connector. That eliminates the extra connectors and wiring losses.
 
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n0ns3ns3

n0ns3ns3

Illustrious
May 25, 2016
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there are couple of problems with your suggestion:
1. what you describe is molex spec - computer parts follow PCIe spec which rates 6pin for 75w. so using such a 6pin on PSU to power 250w (stock) GPU might cause a problem since non of us knows how the internals of this PSU are implemented. i'd assume that a single PSU side 69 connector can do 150w, but going over 200w would not be safe. the connector may melt, the internals can be overloaded. and as you can guess, it might work initially and "go on fire" under continuous load. there is also an environmental factor such as internal case temperature which affected by both ambient and case airflow.
2. using cable directly to the PSU requires knowledge of actual wiring on the PSU which many times different from the device end.
 
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InvalidError

InvalidError

Titan
Moderator
May 18, 2007
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Some no-name aftermarket cables can be of horrible quality but the OEM ones are usually more than fine, especially high-power models. Aftermarket specialty shops like CableMod can make you a set of replacement cables in whatever length, wire gauge and colors and other bling you want - if you're going to get screwed over replacement cable prices to get proper quality ones, may as well have them custom-made.
 
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InvalidError

Titan
Moderator
May 18, 2007
23,815
5,265
108,890

The MiniFitJr and #18 copper wire specs doesn't change just because the connectors get used in PCs. As for not knowing how the PSU is made, you do know how it is made as far as power distribution is concerned: the connectors are labeled V3 and V4 on the PSU, the burden of appropriately splitting your PCIe cable allocation between rails ultimately falls onto you regardless of what cables you use.
 
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G

Gorian

Honorable
Mar 10, 2013
4
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10,520
Hey I looked around a bit and seems like the PSU is ok with up to 250w per PCIe cable and that should be ok with the card drawing 240w. As for the extender I have to assume it's ok with 250w or more otherwise what would it's purpose even be? Also Im seeing people have used this connector for the 280X and similar connectors with similar cards over 200w.

That said I already have two 6pin cables, so Im going to just play it safe and get a pair of 6 to 6+2 extensions.

Thanks for all the info guys.
 
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