Had the same issue 3 months ago when I upgraded the PC after unplugging and replugging cables it started working and it's had no issues since. Yesterday I noticed that the RAM was preforming poorly and both sticks were in single channel. So I moved the cpu fan, reapplied the thermal paste, mounted the fan and moved the RAM into different slots now the PC is having the same issue as 3 months ago and not starting. I have fully rebuilt it twice, tested PSU with paperclip test, tested multiple different configurations with the RAM sticks, tested with/without gpu and still no fans spinning.
Operating System: Windows 10 64-bit
Processor: Ryzen 5 3600
CPU Cooler: Wraith Cooler
Motherboard: ASRock B450 pro4
Video Card: EVGA 1070 SC
Memory: 16GB (2x8GB) Corsair DDR4 Vengeance LPX Black, PC4-24000 (3000)
Power Supply: Corsair CX500M
Operating System: Windows 10 64-bit
Processor: Ryzen 5 3600
CPU Cooler: Wraith Cooler
Motherboard: ASRock B450 pro4
Video Card: EVGA 1070 SC
Memory: 16GB (2x8GB) Corsair DDR4 Vengeance LPX Black, PC4-24000 (3000)
Power Supply: Corsair CX500M