PCIe
PCIe
The RX 580 works well with a 550W power supply, as seen in my secondary setup using a Core i5 9600K and the same GPU paired with a 550W PSU. The main worry is the reliability of the power source. Lower quality PSUs can harm other parts. I don’t know the exact specs of your unit, but since you’ve used it for some time, it seems stable. It draws up to 75W through the PCIe slot, so no extra connectors needed. These cards are generally limited to around 75W per slot according to their design. You’ve confirmed your current model has an 8-pin connector, which matches the requirement.
To purchase one without if your PSU lacks it, you should review the specifications on the manufacturer's site. They usually indicate whether the card needs a power connector. You might also search online for reviews of the model, as images often display the connector type. The RX 580 requires an 8-pin PCIe connector, while some variants like Nitro+ need a 6-pin PCIe connector.
It seems you've filled every available port. The blue PCIe slot is the X16 type—this is where you'll mount the graphics card, as it matches both the physical size and electrical connections, connecting straight to the CPU.
The Corsair CX650 80 Plus Bronze is a solid power supply option. It should work well with your RX 580 8GB and the ASRock motherboard, especially since it uses a 6-pin connector. For future upgrades, you can consider getting one for now and planning another later if needed.