thanks for the response.Hi EduardoG357.
Any PCIe Cable 6+2 pin should fit in that RX 580.
Take a picture of that cable and upload it to imgur.com and upload the imgur.com link here.
What's the PSU brand and model?
as it appears to me, the +2 connector on the side is twisted. Needs to be turned around by 180°
That pic is the correct 6+2 pin connector but the 2 pin is turned the wrong way around(180°). There is only 1 that won't match but its not a problem as the rounded connector fits in the square hole. However 450w is on the small side for a RX580.