I purchased a Sapphire Pulse RX 580 graphics card, and at the same time upgraded my power supply to a Thermaltake Smart 600 watt PSU, but when I power on the PC the RX 580 fans are spinning but no video signal. The minimum requirements on the box is 500 Watts, so I would think 600 Watts would be sufficient. Is it that the PSU is not powerful enough?
Wattage may be above the requirements, but for test PC. If You have lots of drives, fans, extension cards or more power hungry CPU than what their was testing it on You may need to get new PSU with higher wattage.