I wouldn’t use two. Three cables into the psu should be fine with one of them daisy chained into the forth connector of the 4090. Hope that makes sense.
i think 2 should be good because thats what corsair are recommending with their recently released 12vhpwr cable
Its not the connectors at the PSU end that are the issue, its the cables. They are good for 150w each. The new cables they are sending out have higher rated wiring.
I wouldn't use less than 3.
yeah it would be best to ask corssair tech support, but arent these rated for 25 amps?
I used 3 cables and just doubled up on one, i think i ran out of pci-e cables.
So in reply to all of the above I found this post, sounds right to me, I shall use 2 cables to connect to the 4 way plug.
The PCle 8 pin standard is essentially implicit communication. It says that if all 8 pins are connected correctly, the device (GPU) can draw 150W. Even if you make a cable and PS capable of supplying 1.21 jigawatts, the device (GPU) has no way to
know that, so will onlv ever draw upto 150W sustained per 8 pin connector.
Corsair's cables can sustain 300W. But that will onlv be utilised if provided over two 8 pin PCle connections, so their cables terminate with those two 8 pin PCle connections
At the other end, there's an 8 pin connection to the PSU. That connector IS NOT an 8 pin PCle connector. It's a connector bespoke to the PS manufacturer. It can output up to 300W. It only works correctly on the manufacturer's PSU, as the the
pinout is often not the same. (NEVER use a modular cable from a different manufacturer, unless you fancy risking connecting a ground pin on your GPU to a 12V pin on your PSU.)
So, each connector on the Corsair PSU absolutely CAN deliver up to 300W, and using the twin 8 pin PCle connectors at the other end CAN allow 300W to be drawn.
The nVidia adaptor needs four 8 pin PCle connections as each such CONNECTOR only guarantees 150W. You could be attaching for separate 150W PSUs. You could be attaching a nuclear power station over solid copper bars. nVidia can't tell,
so they will only ever draw 150W per 8 pin PCle connector
Corsair have made a cable for THEIR PSUs. They wire the 12+4 pin connector to tell the GPU that 600W is available. They make the gauge of the cabling capable of delivering that. Thev make the PSU end of the cable connect to TWO of their 300W
PSU outputs. Thus, their single cable CAN sustain 600W from their PSUs.
Note that if you plugged in only One connection at the PSU end, only one of the two sense wires would be grounded (the other would be left "open"), and the GPU would be able to tell. Thus, the GPU would only be "allowed" to draw 300W from
that connector.
An 850W Corsair PS absolutely CAN deliver 600W over either two of corsair's twin headed PCle cables, or one of their 12+4 pin HPWR cables. As that leaves only 250W for everything else, including transients, I'm not sure l'd want to. I'd rather
ensure the GPU be limited to 450W to leave enough capacitv for vour other components.