Energy switch effect (black datapoints and lines from Török 2009, see this paper for details) and the twin QPOs fadeaway at low-frequency ratios. The colour-lines after Barret et al. (2005a,b, 2006), Méndez (2006), and Török (2009) indicate the drop in the behaviour of the total energy of the two QPOs (red and green lines) and the drop in the high cohererence of the lower QPO (orange and yellow lines). a) Frequency ratios emphasized in 4U 1636-53 and 4U 1608-52 (3:2 and 5:4) respectively 4U 0614+09 and 4U 1728-34 (3:2). b) 3:2 and 4:3 frequency ratios emphasized in the two sources 4U 1820-30 and 4U 1735-44.