PC build question :)

I am on PCPARTPICKER and I have saw an incompatibility and I am not sure exactly what it means. The error is:

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Warning: The video card PCIe 16-pin power connector adapter is being supplied by three 6+2-pin power connectors. Please ensure that the three 6+2-pin power connectors are not daisy-chained and do not share the same power cable.

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How do I know if the power connectors are daisy chained and if they share the same power cable?

My current list is below:
Video Card: Zotac GeForce RTX 3090 Ti 24 GB AMP Extreme Core Holo Video Card
Power Supply: Corsair RMx (2021) 1000 W 80+ Gold Certified Fully Modular ATX Power Supply

Thanks for any help/advice :)

Generally it would mean the power connectors are on the same cable. Usually with 6+2 or 8 pin connectors they will have their own cable so it is saying make sure each connector has its own cable

On that power supply there are 3 separate gpu power cables

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Originally Posted by david891

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How do I know if the power connectors are daisy chained and if they share the same power cable?

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To expand on Jon's point a bit, a given guage of wire can carry a certain amount of power safely. Thicker wire can carry more. If you connect something (and a 3090Ti qualifies) that can draw a LOT of power, you are either going to want a very heavy duty cable, or several (two, or three). Or, you risk the cable overheating, melting the plastic and a fire. It's the same reason you don't plug a big oven into a wall socket, but use a high-current circuit, heavier cable and a bigger fuse/breaker.

So, daisy-chain?

If you look at a typical old hard drive cable for drives, you'll find a single cable connected to the mobo at one end, and several drive connectors at the other, to plug in two, three maybe even four drives to that one cable. But at the mobo end, all those drives are run ning over one cable.

For your power cable, what you don't want is :-

PSU end - one cable to GPU
GPU end - several multi-pin connecters, linked to each other.

That ^^^ is the "daisy-chain". Like the old flower arrangement, where daisy one links to daisy two, daisy two links to daisy three, etc. to form a daisy necklace.



What do DO want, is

PSU end - GPU cable 1 - ONE connector at GPU end

PSU end - GPU cable 2 - ONE connector at GPU end

Maybe a third, as well.

If they're separate CABLES, each with a single connector, the GPU won't overload the cable.

If it's one cable from the PSU, and several connectors all on the single cable at the GPU end, then the entire current passes down that single cable, and they aren't rated to handle what a 3090 (or less) can draw down it. And that's the fire risk.

If there are two or three cables coming out of the PSU, each with ONLY ONE connector at the GPU end, that isn't daily-chained.

Some usually cheaper PSUs even provide a plug-in adapter at the GPU end. That plugs into the GPU end of the cable, and has two connectors on it. Again, clearly, all the current has to run down that single cable. Not a good idea on something as power hungry as a top-end GPU.

Oh, and Im not an engineer or electrian so this is opinion only, not advice. The best bet when there's a fire risk may be to take the PC to a good local computer shop, and ask them.

I just thought I'd add that these days, most power supplies have a single 12V rail from which power is drawn. There's usually a printed panel on the side of the PSU that states how much of the total power can be drawn from each rail (12V, 5V, 3.3V). Some older PSUs used to have multiple 12V rails, so by making sure that the GPU connectors weren't daisy-chained, it ensured that the 12V was drawn from different rails & therefore less likely to overload a particular 12V rail.

There's been a couple of very interesting YT videos on Gamer's Nexus recently, with Steve talking to Corsair's Jonny Guru about PSU internals. Worth a visit.