Question Motherboard RGB lights on but PC turned off

[HueJanoos]

I was attempting to install a new GPU into my already working system until I flipped the power switch and pressed the power button and nothing happened besides the RGB lights from my motherboard that already turned on from the PSU switch. I've already tried plugging in the wires, remounting GPU and RAM, reseting CMOS, and I even tried to get a beep code by removing everything besides the CPU and I got not beep code. I decided to try remounting the old GPU to see if my new GPU was a DOA, but for some reason that did not work either. I can hear my PSU hum so I don't think that's the problem.
CPU: Ryzen 5 3600X,

MOBO: Asus TUF Gaming B550 Plus

RAM: 2x8GB 3200 Corsair Vengeance

GPU: GTX 1660 (trying to put in a 3060 ti)

PSU: Corsair 650 RMX

 

[HappyTrails]

Have gotten this issue when overclock here. Everything come on but no video to monitor. Sometimes system reset let me go into bios and I just check settings and save usually pc comes up. Another way that works I think is when hit reset button on pc. Last resort is clear the cmos have done that many times only it difficult on my pc due to vertical gpu cmos battery behind it. Needless to say I not like clear cmos method so I take easy on overclocks now. To put it in perspectives gains so minimal it was lots of work for very tiny gain. Notice this on cpu as well have put pc thru OC tests. Sometime also hear others say good is reseat video card. Not sure why it works I never do that myself. For your pc would suggest clear cmos, remove battery, hold power button in should clear it.

 

[HueJanoos]

Have gotten this issue when overclock here. Everything come on but no video to monitor. Sometimes system reset let me go into bios and I just check settings and save usually pc comes up. Another way that works I think is when hit reset button on pc. Last resort is clear the cmos have done that many times only it difficult on my pc due to vertical gpu cmos battery behind it. Needless to say I not like clear cmos method so I take easy on overclocks now. To put it in perspectives gains so minimal it was lots of work for very tiny gain. Notice this on cpu as well have put pc thru OC tests. Sometime also hear others say good is reseat video card. Not sure why it works I never do that myself. For your pc would suggest clear cmos, remove battery, hold power button in should clear it.

I just tried that and it's exactly the same

 

[HappyTrails]

An older method is to take out battery and have jumper on overnites. Just need to get juice out of motherboard to force bios to come up.

Another thing to try is put back old gpu see if everything still fine. If is then do safemode boot and DDU old drivers then swap videos cards see if start up.

 

[HueJanoos]

So I took it to my local repair shop today and he tried using his own PSU (I didn't have a second) and attempted to get some sort of post code which should have happened after removing everything except for the CPU in. After the same exact thing happened after those tests he deemed the motherboard to be defective.