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.
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.
If your GPU has two power connectors you should always use two runs from the PSU.
You only have to ask yourself why they would bother with the second connector if it was okay to just attach a little extension to the end of a single cable.
Some cards may run fine with this setup, but you’re going to be increasing fire risk by potentially running more amps down a wire than is safe to.
You only need to ask yourself why the PSU manufacturer would bother including the second connector on the same cable if it wasn’t ok to use it.
If you use a third party extension/splitter that would be another story but it doesn’t look that way in the diagram.
I seem to remember they started doing those daisy chain power connectors back in the SLi days. Take the GeForce 6800GT for example, which was a single slot card rated for 67 watts and had a single 6-pin power socket. You could safely drive two of them in SLi on a single 150 watt PCIe power cable. Hell they’d probably both run fine on motherboard power.
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.
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.
Is this a thing with new GPUs? I’ve always connected my GPUs with 1 cable there was no option for 2. I currently have a RX5700 XT.
I am using a RX 6700 XT on one cable as well and it’s perfectly fine. If your PSU has a second cable you can run that to be sure, but if not like mine don’t worry about it. It’s only certain corner cases like extreme overclocking, or certain cards and PSUs that violate the specifications that actually cause issues. The Radeon R9 295X2 would be an example of this. 12VHPWR actually runs a similar amount of current per wire, with an even smaller connector, as a daisy chained 8 pin setup. You should not use third party splitters though if you want to be safe.
I have a 7900 XTX, having upgraded from a 5700 XT, yeah it’s a thing, and it is also a much chonkier boi. Weighs like 2.5 kilos, barely fits my case.
I knew GPUs had gotten bigger but then I built an all new PC, upgrading from a 2080 to a 4090.
Holy shit. That thing is fucking huge, man. I was literally stunned pulling it out of the box. Just set it down and stared at it for awhile trying to process technological progress. It’s like 8 times the size of the GPU I had in 2006.
As I type this I"m in the process of building a new computer, going from a GTX-1080 to an RX7900GRE, and it’s relatively small, I got a 2-fan Asrock Challenger one and while it’s bigger than the 1080 it’s not as big as some I’ve handled. It’s amazing how they managed to pack the 1080 into such a small package. I guess the blower fan helps.
