Time evolution of the simulated total energy (upper panel) and its relative deviation from its conserved value (lower panel) as obtained by the 2D Orszag-Tang test using GOEMHD3 in dependence on the mesh resolution of 128² (red), 256² (green), 512² (blue), and 1024² (magenta) grid points. The black line overlaid in the upper panel corresponds to the volume energy density of 0.0697 rescaled from the surface density that was obtained by the ATHENA code run for 1024² grid points.