Powering graphics card

Soid · July 24, 2022

I recently built a pc with an MSI 3080 Ventus 12 gb. The card has two 8 pin power connectors on it. My power supply (HX1000i) came exclusively with 8 pin cables that have the two 8 pin (two 6 pin with the 2pin split off) connectors on the PCIe end from the one 8 pin power supply end. So, theoretically, I could fill both power slots with one cable. My thinking was though, was that if the card has two power inputs, then it couldn't be satisfied by one power output. I used two cables, and twisty tied back the second connector on each cable (just to keep them out of the way). I don't know if that's right or not, or if I could have just used one cable.

The manual is extremely vague about how those two 8 pin connectors should be powered. They just say vaguely to plug in what the card requires (thanks manual... you're supposed to tell me what that card requires. Jerk.). I could not find any specific instruction on what the power requirements are.

I watched a few videos, including the LMG PC build guide. They were all similarly vague. I'd even call them evasive.

So my question is... How the heck should I power this card? It seems very plausible that I could just use one cable with the two sets of 8 pins, from one power supply plug. It also seems plausible that It'd be require two plugs, one plug for each 8pin input on the card. The manual didn't tell me. The manual in the box and the manual online both sucked.

What is correct?

Poinkachu · July 24, 2022

15 minutes ago, Soid said:

I recently built a pc with an MSI 3080 Ventus 12 gb. The card has two 8 pin power connectors on it. My power supply (HX1000i) came exclusively with 8 pin cables that have the two 8 pin (two 6 pin with the 2pin split off) connectors on the PCIe end from the one 8 pin power supply end. So, theoretically, I could fill both power slots with one cable. My thinking was though, was that if the card has two power inputs, then it couldn't be satisfied by one power output. I used two cables, and twisty tied back the second connector on each cable (just to keep them out of the way). I don't know if that's right or not, or if I could have just used one cable.

The manual is extremely vague about how those two 8 pin connectors should be powered. They just say vaguely to plug in what the card requires (thanks manual... you're supposed to tell me what that card requires. Jerk.). I could not find any specific instruction on what the power requirements are.

I watched a few videos, including the LMG PC build guide. They were all similarly vague. I'd even call them evasive.

So my question is... How the heck should I power this card? It seems very plausible that I could just use one cable with the two sets of 8 pins, from one power supply plug. It also seems plausible that It'd be require two plugs, one plug for each 8pin input on the card. The manual didn't tell me. The manual in the box and the manual online both sucked.

What is correct?

If you can use 2 separate cables , use separate instead of daisy chain.

Daisy chain can work, but yours is a high power card which usually sensitive to voltage drop, not to mention RTX30 series sometimes have a power spike.

I use 2 separate PCIe cable for my 3060ti, zip-tied the daisy chain part of each to it's base cable so it won't flail around.

manikyath · July 24, 2022

the PSU is designed with in mind that one cable can provide 300 watts (2 8-pins => 2x 150W)

so in theory you could power your card with the two plugs on a single cable.

the reason i say "in theory", is that there's voltage loss across the cable, that is proportional to the power draw hooked up to said cable. in simple terms, this means that if you wire your GPU to two separate cables it's getting a more stabile power delivery compared to what it'd get with one cable with two plugs on the end.

so, if you have two cables, use two cables.