I saw this picture while looking at overclocking guides and I wondered if I may have my power setup incorrectly. My GPU is currently connected exactly like the don't do this diagram.
this post was submitted on 27 Aug 2024
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The concern is that really running too much current / many amps through too thin of a cable risks melting the cable, which can in turn cause a short and fry things.
For a cable meeting the minimum specification, for one 8-Pin PCI connector it would be rated to handle about 12A / 150W. L
Your card can draw up to 300W. If your second PCI power connector is a “pigtail” off of the first, then the first run of cable is taking about 25A at full load.
If the cables are thick and overbuilt, that’s bot really an issue. If the cables are thinner and have a lower current rating, they could melt.
Best practice is to split the connections across the power supply’s available ports.
A well built power supply will have a current limit on the connector to prevent the cable melting problem, but that means if you have a card that needs 200w, but only power it via 1 connector you are going to run into problems
12hpwr/6+6 will do 600 watts using a lot less copper than what you'll find in 4 8 pin pcie cables.
The ATX standard allows for a 5% voltage drop. This shitty 2.1 star rated extension cable uses 18 gauge wire which is typically the worst you'll see in a cable. Using this calculator 30 amps on an 18 gauge 3 foot cable leaves you with 0.1v of drop which is within spec. And there's 3 +12v wires in every 8 pin cable. You'll be fine.
Yes, this is the way. I've had to do the maths manually without one of those calculators before, but people still wouldn't believe me.
Best advice is to always do what your PSU maker recommends. If they put the connector on there it probably means they want you to use it.