I barely managed to get my new Corsair RM750 PSU in the phanteks p300 case because of the mounting HDD on the bottom, the cables are flexing pretty hard I guess? Is that ok? https://ibb.co/MDbL6FThttps://ibb.co/SJNV37Y
Not a problem whatsoever. There are many cases with very little space for PSU cables, you simply have no choice. This case wouldn't exist if it would be a problem.