My pc powers on for a few seconds then shuts down. After numerous startup attempts it posts, boots up and runs normally. I tested the PS with the PSU tester and it tested OK. I have replaced the motherboard and tested with another video card and the problem persists. I believe it’s a PS issue, but EVGA support thinks the problem is elsewhere.
EVGA Supernova 850B2: Power Supply
Gigabyte GA-AB350-Gaming 3: Motherboard
AMD Ryzen 7 1700: processor
Sapphire Radeon RX Vega 56 8G: Video Card
Corsair Vengeance LPX DDR4 2X8GB: Memory
Windows 10 Pro 64 Bit: Operating System