Hi everyone. I recently built a new system, and while I thought everything went fine, it appears I may have an issue.
Here's the specs:
   CPU - i9 9900K (w/DeepCool Castle 360mm AiO)
   MB - Gigabyte Z390 Aorus Pro WiFi
   GPU - Gigabyte Aorus RTX 2080 Super Waterforce
   RAM - 32Gb G.Skill Trident RGB DDR4 3600
   PSU - EVGA SuperNOVA G3 850W
   SSD - 500Gb WD NVMe SSD
   HDD - 1Tb WD Blue Caviar @ 7200 RPM
 
At first, because my case has a window, I only noticed an LED on my MB lit while the computer was shut down. I thought it was some sort of "standby" light, it wasn't until I looked into turning it off that I discovered it (CPU status light) shouldn't be on at all. Upon closer investigation I learned the 2 fans on the GPU's AiO radiator were still spinning after shutdown and a couple of LEDs on the GPU (not the decorative rgb kind) also light up only after shutdown. Finally, the PSU fan continues to spin after shutdown.
 
Edit: In case it's important, the MB has an 8+4 CPU power connector and the GPU has 2x 8pin power connectors.
Also, the LEDs on the GPU that are only lit after the computer is shutdown are meant to indicate "Power Cable Disconnected" when solid, as they are or "Abnormal power supply" when blinking, which they aren't.
 
The MB manufacturer thinks it's either the PSU or a Windows issue. I don't have a spare PSU laying about, or that would be my first test. I also don't have a spare HDD to try a fresh OS install swap. Is there a way to troubleshoot this issue without spare PSU or HDD? Should I just order a new PSU?
 
While the computer has been running like a champ for about 2-3 weeks, I don't want this issue to cripple the system down the road, so any help is greatly appreciated. Thanks in advance!
 
 

Go into your bios and enable erp mode. See if that fixes the issue for you.

Ok, first, thank you both for replying.
 
Cool GTX, here's the answers to your questions:
PSU provided cables only.
I have built PCs before, this is my first modular PSU but I had no doubts about which ends were which.
I had already disabled 'Hibernate' in Win10
Gigabyte (MB manufacturer) didn't verify BIOS settings at all, it never came up.
I disconnected the powered USB hub's power and everything was still the same.
I have not yet tested the PSU using the supplied cap. If all else fails I will do this.
I have not yet disconnected the case to mb power switch to test that. I don't think my MB has buttons (just flipped through the manual again.)
 
Sajin, as I mentioned in my panic post above, I enabled ERP mode in my BIOS, and when I shut down, none of the "problem LEDs" were lit and the GPU fans stopped. I haven't shut down a second time, to verify this, because of the reboot scare I just had.
 
So does this BIOS setting solve everything? There are no problems with my PSU, GPU or MB?

Shut down again, confirm that all problem LEDs are off and fans stop.
But I've got the same weird problem when starting it back up. I made a short video of what happens and what I have to do to get it to reboot. Can't post links here, I guess, so just figure out how to youtube the following: qEWoYIhmACw

BIOS already updated to F11.
I will admit that I have very little experience with BIOS settings. I watched countless videos to prepare for this modern build but I'm sure I missed some things. Feel free to ask about anything, I'll be happy to check, and maybe snap a photo or two.

I Double checked, BIOS still F11.
Also, XMP has the profile set, working fine at 3600. (Confirmed in Windows and CPU-Z)

Squeemeister
Shut down again, confirm that all problem LEDs are off and fans stop.
But I've got the same weird problem when starting it back up. I made a short video of what happens and what I have to do to get it to reboot. Can't post links here, I guess, so just figure out how to youtube the following: qEWoYIhmACw

Try this...
 
#1 Load optimized defaults inside the bios.
#2 Save and exit the bios and load into windows.
#3 Restart pc and access the bios.
#4 Enable erp, and save and exit the bios and load into windows.
#5 Shutdown pc, and then try starting the pc.

Hmm. Might want to try some older bios versions to see if that might resolve your issue.

It was probably causing some kind of weird grounding issue with that connector plugged into the PSU. I wouldn't spend too much effort in figuring out the why... It will usually come with more grief than it's worth.

bob16314, thanks for your reply. I'm at work rn, but I will be sure to check those BIOS settings when I get home. I'll keep you posted.
 
UPDATE: Nope, those have always been set to OFF, both places.

Squeemeister
But you know, what you said, "It seems that the mobo's LED headers may be providing voltage when your PC is powered off and feeding it back into the PSU." got me thinking... what if it's the other way around? What if the RGB Splitter is always demanding power from the PSU via SATA but with nowhere to send it, since the fans are forced OFF, the excess is just spilling into the MB's header and then finding its way to any nearby outlet? Would that explain the PSU fan remaining on too? Since the Splitter is basically saying "gimme gimme gimme"?

I don't think that's possible.
 
Did you turn off the headers in the BIOS and/or software and see if it mattered?..Or you could just simply unplug the cable from the header.
 

The white LED on the rgb hub is lit even when pc is shutdown and the hub is only connected to the D_LED1 header on mb. The manufacturer of the hub doesn't look like they're going to reply to my email, so I'm unable to get any straight answers. As much as I don't want to deal with it, I might have to swap out the PSU with a new one just to completely rule out "PSU problem". I'll let you know the results once I work up the patience to rewire this beast.