QPO amplitudes from RAMSES numerical simulations. QPO relative amplitudes in X-ray (0.5−10 keV) bremsstrahlung (in red) and optical cyclotron (in black) are shown for two different masses M_WD = 0.66 M_⊙ (filled symbols) and 0.85 M_⊙ (open symbols) as a function of the column cross section. Full and dotted lines are polynomial fits to the data points. Also shown as horizontal lines are the observed upper limit in X-rays (red line) and the mean optical amplitude (dotted line) and range (shaded area) from the present observations.