Is there a method to make one PSU with an 8-pin slot deliver more than 150W?
Is there a method to make one PSU with an 8-pin slot deliver more than 150W?
I’m thinking about switching from the RTX 3090 to the RTX 4090. Right now I have only two 8-pin PCIe cables connected to my PSU (Corsair HX1200 80 PLUS PLATINUM). I thought because each cable can handle about 288W, with a total of 576W, I could use them without needing additional power cables, since I’m not sure how much power I’d need in an already built system. But I was told each cable is limited to a maximum of 150W. Can I still get them to draw more power?
Looking at the PSU documentation, it says that when in the “SINGLE” mode, all connectors can use the full output of the +12V rail, but in “MULTIPLE” mode each connector has Over-Current Protection, limiting it to 40A per cable.
Does this affect the situation? Or is the problem still there?
The GPU side of the cable has a power rating of 150W for an 8-pin connector. The PSU side is designed to accommodate the specifications Corsair implemented in the power supply unit. It's common to adjust the modular cabling in an existing system, which is why these options are available. For your setup, consider using a Corsar Type 4 12VHPWR cable.
Most likely not.
1) I heard Nvidia voids your warranty if you don’t use their adapter.
2) I’m not eager to install another cable, your idea would require me to remove and then install a more complicated one. It’d be much harder. Instead, I’d just install another 8-pin cable and connect the three cables to Nvidia’s adapter.
Also, isn't the 150W just a safety buffer? Will it simply not draw more than that amount?
3 8-pin connections will only provide 450W, so you shouldn't attempt overclocking or use a boost profile beyond that.
Corsair offers warranties for the hardware if you use the cable, and they may repair your card or replace it if needed.
I believe you're greatly underestimating the effort required to replace the cables. It might only take about five minutes, especially if your chassis allows removing the PSU from behind for extra space. Unless you have a very compact setup with enough room for a 1200 PSU and a 4090...
In the scenario of a 4090, restrictions are applied via the four sense pins on the 12VHPWR cable. On devices such as your 3090, the card tends to operate according to its own requirements. The PSU imposes limits on the available rails. I would need to verify with the HX1200 whether each modular connector supports OCP, which seems unlikely. However, a 150W figure serves as a general guideline with significant room for error. The actual performance hinges on factors like wire gauge, whether connections are soldered or crimped, etc. Even inexpensive PSUs typically use at least 22 gauge wire, which should support around 60W per 12V wire (depending on length). Corsair likely uses 18 gauge, allowing them to safely handle higher wattage from their Type 4 8-pin. Remember that EPS 12V is rated for up to 336W, which corresponds to four 12V wires or about 84W per wire. Therefore, each Type-4 connection should ideally handle up to 252W, with 288W being a reasonable estimate. For the 4090, you’d need to connect at least three 8-pin devices to an adapter to reach a total of 450W. Unless you modify the sense pins to force a lower draw from just two PCIe 8-pin connections, I wouldn’t recommend it. Personally, I’d prefer Corsair’s Type 4 or a model from Cablemod.
The HCS terminals on the Corsair modular board are designed for 13A per pin. With three 12V pins, the total is 39A before it overheats. A safe margin of 25A per terminal is maintained. This is why Corsair employs two 8-pin terminals on the modular board for the 600W 12VHPWR cable. The initial PCIe connector in a Corsair cable is also of HCS standard and can safely handle 300W.