I recently purchased a Corsair AX750 Gold power supply and an ASUS TUF Gaming B550-PLUS WiFi II motherboard, planning to install them in a new case while keeping my other components. Before connecting everything, I wanted to test my RGB fan controller setup, so I powered on the PC without a CPU, GPU, or RAM. While I expected the motherboard to boot into the BIOS and power the fans, the power button didn't function as expected.
After taking everything apart for a closer look, I connected only the PSU to the motherboard, ensuring I had plugged in the 8-pin and 24-pin connectors. While the motherboard lights up, it doesn't boot when I try to short the power and ground pins.
Is there a way to determine if the PSU or motherboard is defective without connecting other components? I'm worried about damaging parts if something's wrong. I've also heard that the AX750 might have a silent mode, preventing the PSU fan from spinning until there's a load, which might explain why my initial tests didn't work. After some trials, I found that the paperclip test did work, and the PSU fan turned on briefly before likely entering silent mode. Any advice?
2 Answers
For diagnosing your PSU, it’s a good move that you tried the paperclip test. If the fan briefly spins and then stops, that could indicate it's in silent mode due to no load. Just to be safe, try connecting some basic components (like a single stick of RAM) to see if the motherboard can at least POST with something attached. However, it sounds like you're wise to avoid connecting everything until you troubleshoot further!
It's normal for the motherboard to power on the fans, but if it can’t complete POST (the Power-On Self-Test), you'll never get to the BIOS. Sounds like you're on the right track. When you short the motherboard's power header, it should also trigger the fans and lights.
Make sure you're also checking your connections. If the front panel header isn’t responding at all, that could be an issue with the motherboard.
I tried shorting the front panel header directly and nothing happened—fans stayed still, and the RAM didn’t light up either. But I noticed the PSU runs for a moment when I short the 24-pin header alone, so I think it’s entering silent mode.