I believe the CPU cooler is a Noctua NH-L12. Given the design and size of the heatsink and the location of the CPU socket and other motherboard components, it may not be possible to rotate the heatsink 90 degrees.
BTW the NH-L12 is discontinued. Its height without a fan on top of the heatsink is 66 mm. The NH-L12S is the replacement model, but it's taller at 70 mm which is too tall for the Ghost S1. So get the NH-L12 while you can. I would try replacing the 92 mm NF-B9 PWM fan that comes with it with the Noctua's new slim NF-A12x15 PWM 120 mm model.
BTW the NH-L12 is discontinued. Its height without a fan on top of the heatsink is 66 mm. The NH-L12S is the replacement model, but it's taller at 70 mm which is too tall for the Ghost S1. So get the NH-L12 while you can. I would try replacing the 92 mm NF-B9 PWM fan that comes with it with the Noctua's new slim NF-A12x15 PWM 120 mm model.