The power supply doesn’t start with a jumper but works with an empty motherboard. Did you overlook a step?
The power supply doesn’t start with a jumper but works with an empty motherboard. Did you overlook a step?
I possess a Seasonic SS-850KM Active PFC F3 Power Supply and intend to connect it to an eGPU. Since it won’t power on directly, I tried the PS_ON jumper or used a paperclip trick, but it didn’t work. The fans spun briefly before shutting off again, and there seemed to be a clicking sound. When I connected it to an old empty motherboard via its 24-pin port and used the power button, it worked perfectly. I suspect the issue might relate to sense lines or a missing resistor, as mentioned in the linked discussion.
The sense wires are located on pins marked with two numbers: In short, each voltage has a dedicated wire that travels from the 24-pin connector back to the power source, providing the actual voltage reading at the motherboard port. If there’s a voltage drop along the cable to the board, the PSU can compensate by slightly boosting the voltage on that line (for example, sending 5.1V through the cable so 5V reaches the connector while only 0.1V is lost between the board and PSU). The 24-pin connector doesn’t need to be connected to the motherboard itself; however, if no real power is drawn from it, the PSU might shut down. You could bypass this by linking a fan to ground and adding 12V to the 24-pin connector, or using LED strips or an incandescent bulb—cheap options like motorcycle signal lights or automotive parts are common choices. You might also be misled by a hybrid or fully passive fan mode, which can cut power delivery if insufficient current is present.
If the sense wires are only measuring voltage at the end of the wire, it likely shouldn’t prevent the PSU from turning on. Since your eGPU is connected via the power supply’s PCI-E connector, there should be some load there. The lack of load through the 24-pin connector suggests the issue might be elsewhere. You mentioned you can power it up without any other load using an empty motherboard—this confirms the problem isn’t with the main power path. You also have resistors available to add load, though you’re unsure about the right values. A multimeter reading shows no voltage, indicating the fan or other components aren’t receiving power either.