RM750. My motherboard, GPU etc occasionally receive no power after restart

[jawline]

After cutting power to my machine from the plug or from the switch occasionally my motherboard and GPU don't receive any power for a while. It will start lighting up and be ready to power after a while once I remove the cable and reconnect it. What could be causing this issue?

[jonnyguru]

You're unplugging and/or flipping the switch on the back of the PSU, why?

 

And I don't quite understand the problem. AFTER you unplug and plug your PSU back in, it takes a while for the PC to start?

[jawline]

1. Trying to diagnose hardware issues, take it apart, whatever.

 

2. It's not taking a while to start, it's not being supplied with power at all (Mobo and GPU have LED indicators). This is usually fixed by removing the power cord from the machine and waiting for some time before re attaching it.

 

Could it be a fuse tripping? It's such an odd issue but as my motherboards top PCIe lane recently died (stopped supplying power) for whatever reason I want to double check anything that could make it happen again.

[jonnyguru]

The light on the motherboard is from the +5VSB on the PSU. If the PSU is not supplying +5VSB to the motherboard, there could be a couple reasons:

 

1. As you suggested, a short. Cycling the switch on the back of the PSU resets the short circuit protection.

 

2. The power good signal timing is off. This could be a fault of the motherboard or the PSU. If it's off by only a few milliseconds, that could explain why it works sometimes and not others.

 

3. Just a bad motherboard.