Two fresh PSUs aren't functioning, the old one is working.
Two fresh PSUs aren't functioning, the old one is working.
I’m really struggling right now. I own a 2017 system with an MSI Z370 board, a GTX 970 and a Seasonic S12ii-520 PSU. Yesterday I upgraded to a 3070 and a quiet dark power 12 1000W. After work I came home, swapped the components and still nothing. I spent the night trying to fix it. Eventually I went to the store, returned with an RMA for the bequiet and brought back a Seasonic GX-1000. The same issue persists—only when I connect the green and black pins short while the 24-pin is in the motherboard. It powers up, shows the CPU debug lights, but shuts down instantly. This doesn’t happen with the older 520W Seasonic. What could be going wrong? Why does it work with one PSU but not others? If the motherboard is bad, why would anything function at all? What’s the problem here?
Did you reuse any modular cables? I connected the 4/8pin CPU power with the proper CPU cable, not a PCIe one.
All modular cables don't match—brands or even models from the same maker may not work together. Ensure the 24-pin connector is completely seated; gently slide a few fingers under the motherboard so pressing the connector doesn't warp it. Verify the CPU connector is fully connected. Check that the power supply's on/off switch is set to ON.
It's unlikely two faulty PSUs are the issue, but it's not impossible. Would the 3070 fit with a 520W unit?
Begin by halting PS_ON for a brief period until the CPU debug LED vanished. The power switch remains unresponsive.