Quick Question about GPU power cables

[Gravemind]

I'm getting an RX 7900xtx and it needs 2 8-pin connectors for power.

Now should I run a single cable with both connectors(2x 6+2) and call it good, or is it safer to run 2 dedicated 6+2 cables, 1 to each slot? And each plugged into its own independent port on my PSU

My EVGA PSU came with cables for either daisy chaining or singular use, and I'm getting a lot of conflicting messages from quick googling. How messy my case is doesn't bother me, just whatever's best.

[aledsav1]

singular use 2 cables

[DoctorNick]

38 minutes ago, Gravemind said:

I'm getting an RX 7900xtx and it needs 2 8-pin connectors for power.

Now should I run a single cable with both connectors(2x 6+2) and call it good, or is it safer to run 2 dedicated 6+2 cables, 1 to each slot? And each plugged into its own independent port on my PSU

My EVGA PSU came with cables for either daisy chaining or singular use, and I'm getting a lot of conflicting messages from quick googling. How messy my case is doesn't bother me, just whatever's best.

What PSU you got?

[Gravemind]

3 minutes ago, DoctorNick said:

What PSU you got?

https://www.newegg.com/evga-supernova-1000-gt-220-gt-1000-x1-1000w/p/N82E16817438221?Item=9SIB7WMJKF1738&Description=power supply&cm_re=power_supply-_-17-438-221-_-Product

[DoctorNick]

2 minutes ago, Gravemind said:

https://www.newegg.com/evga-supernova-1000-gt-220-gt-1000-x1-1000w/p/N82E16817438221?Item=9SIB7WMJKF1738&Description=power supply&cm_re=power_supply-_-17-438-221-_-Product

PSU is fine and use two cables

[mariushm]

Using one connector from each cable , so two separate cables, is a bit better. 

It would work with just one cable and using both connectors on one cable, but you're putting more stress on the connector that plugs into the power supply and the cable will get warmer. 
More wires between power supply and video card means less losses in the cables and the connectors are also under less "stress".

[PDifolco]

16 minutes ago, mariushm said:

Using one connector from each cable , so two separate cables, is a bit better. 

It would work with just one cable and using both connectors on one cable, but you're putting more stress on the connector that plugs into the power supply and the cable will get warmer. 
More wires between power supply and video card means less losses in the cables and the connectors are also under less "stress".

Using a single cable will draw more than 350W (30A @12V) from a single PSU rail isn't that a bit dangerous (risk of power trip) ?

[mariushm]

44 minutes ago, PDifolco said:

Using a single cable will draw more than 350W (30A @12V) from a single PSU rail isn't that a bit dangerous (risk of power trip) ?

That power supply has a single 83A rail for 12v. 

 

The miniFit Jr connectors are rated for a minimum of 9A per pin, so a cable (regardless of how many connectors are at the other end) could in theory transfer a minimum of 3 pairs x 9A per pair x 12v = 324 watts. The minimum is for cheapest pins made out of folded metal, on higher end power supplies they use pins rated for higher current (around 13A).

The higher end power supplies also use thicker wires, for example AWG16 instead of AWG18. 

 

On most power supplies, the connector on the power supply end has 4 12v wires and 4 ground wires so that you can reuse the connector with CPU cables (EPS) which also has 4 12v wires and 4 ground wires. Some cables take advantage of these 4 12v pins available on the power supply to make the cable a bit different :  the first pci-e 8 pin will be connected to pins 1 , 2 and 3  and the second connector will use pins 1, 2 and 4 

This way you have 4 x 9A x 12v = ~430w minimum available on the power supply connector, going to 2  150w max plugs at the end of the cable 

I don't know if evga does it like this ... they do separate the cpu connectors from the vga connectors, so maybe the vga connectors have only 3 12v pins and 5 ground pins, maybe they preferred having nice looking cables instead of more complex cables)

 

Regardless, the video card may pull 350 watts, but around 50-60 watts of that is taken through the pci-e slot and only around 300 watts is taken from the extra pci-e connectors. 

So while the connector going into the power supply will be kinda abused, sitting close to 90%-ish of its maximum capacity, it should be fine and you wouldn't have any problems.

 

But, as I said, it's better to use two separate cables, so that the power pulled by the video card will be spread across two connectors on the power supply, and each connector will be "happier", working at maybe less than 50% of its maximum rating.