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.
Yes. I too did this once with a friend’s build, scratching my head why performance was terrible and power usage didn’t go above 250W.
The manufacturer is concerned that they will be pulling a ton of power from both connectors. Sometimes the second connector is just for ancillary power silly or balancing, in this instance they are saying that they’re planning on your card pulling as much power as possible.
You might find that in heavy situations, or on hot days, your power supply overcurrent will trip out and your system will crash. If you have the second connector, I’d connect it, and if you’re worried about having a plug dangle around just tie it back with a tywrap or some electrical tape so it’s nice and clean.
Not all PSUs even have a second cable. Mine sure doesn’t.
Technically it’s fine to use daisy chained connectors. People get into trouble though with badly built power supplies, extreme overclocking, or cards like the R9 295X2 that blatantly violate the specifications.
Older PSUs sometimes have trouble with new GPUs. It generally happens because new cards have large power transients that the older spec didn’t take into account. Sometimes running a second line fixes this for one reason or another, but not always. 12VHPWR actually uses similar current per wire or per cross section area of wire as a daisy chained setup, if not a little more.
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.
Its been years I ain’t checkin’ that shit. I’ll make sure to forget this for the new build.
If the GPU has two power inputs, you don’t do the “don’t do” diagram. Period.
Like other commenters have input, there are specific situations where you’re probably fine.
If you have to ask, just fix your wiring to one of the green check configs.
This is literally how house fires start.
Crap I was hoping someone wouldn’t say this. Rewiring its going to be a mission.
Only if you buy a shitty PSU. Quality ones have lots of protection circuits so worst case the PC would randomly shut down in high load situations.
Even then if the manufacturer put two connectors on the end of the cable they made sure to put large enough conductors to handle at least the max load of the connectors specifications. Again if it’s not a shitty no name brand. Probably with a good safety factor as well.
It’s not like 300-400W is that much energy in the grand scheme of things, so thicker wires wouldn’t even be expensive.
