This paper compares six different numerical models to predict the performance of an X-shaped vertical-axis wind turbine, offering insights into how it works in 3D when its blades are fixed at specific angles. The results showed the 3D models here reliably predict the performance while still taking this turbine's complex aerodynamics into account compared to 2D models. Further, these blade angles caused more complexity in predicting the turbine's behaviour, which is highlighted in this paper.