A recent study of X-ray emission from non-magnetic cataclysmic variables1 concludes that most of the hard (≳2 keV) flux is produced in a corona formed by the accreting material around the white dwarf. EXOSAT observations of SS Cygni (see accompanying paper)2 strongly support this model, confirming several of its detailed predictions. The model suggests that soft (≲2 keV) X-ray production is controlled largely by transport processes into the white-dwarf body which remove most of the energy from the accreting matter. I point out here that, because even weak magnetic fields can exert a marked influence on transport processes, tbere is a natural explanation for the quasi-periodic oscillations seen in soft X-ray observations of dwarf novae at outburst3-5. I suggest further that the puzzling behaviour of the `DQ Herculis' system (DQ Her, V533 Her and AE Aqr) may be explained in this light.