From what you've posted it doesn't have an 8 pin power connector and adapting molex connectors to 6/8 pin is really sketchy. Only from the listed connectors it looks like a really crappy power supply that I wouldn't even try to place near a RX 580.
You can use the FSP if there's no other alternative.
You definitely can't use the one you have now. Even if the insides weren't hot garbage and you didn't have to use the terrible solution of molex-PCIE adapters, 17 A on the +12V rail means you'd still only have about 200W of +12V power. A 580 at load can go over 200W all by itself