We present Monte Carlo simulations of discotic molecules using the Gay-Berne potential with shape (κ) and energy (κ′) anisotropies. Following the previous work of Bates and Luckhurst [J. Chem. Phys. 104, 6696 (1996)] at κ=0.345, κ′=0.2 when we determine the sequence of different phases at the same reduced pressure P*=50, we find an additional phase at low temperatures corresponding to an orthorhombic crystalline phase and we characterize it. Keeping the shape anisotropy fixed at κ=0.2, we determine the evolution of the phase diagram with varying energy anisotropy. At high κ′, low anisotropy, the system is not able to build columns while at low κ′, the system exhibits both orthorhombic crystal as well as hexagonal liquid crystal phases over a wide range of pressures and temperatures. The domain of stability of the nematic phase is found to systematically shift towards higher pressures as κ′ decreases.