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We present a broadband spectral-timing analysis of SMC X-1 at differentintensity states of its super-orbital variation using 10 Suzaku and 6 NuSTARobservations. The spectrum in all the states can be described by an absorbedpowerlaw with a high energy cutoff and a black-body component along with aniron emission line. Compared to other supergiant HMXBs, the Fe K$\alpha$ lineequivalent width is low in SMC X-1 - from less than 10 eV in high state to upto $\sim$ 270 eV in the low states. The spectral shape is dependent on fluxwith the hard X-ray spectrum steepening with increasing flux. We also report ahighly variable normalisation of the power-law component across these 16super-orbital states. Pulsations in the hard X-rays for both the instrumentswere detected in all but two observations. The pulse profiles are nearsinusoidal with two peaks and the relative intensity of the second peakdecreasing with decreasing luminosity. These findings suggest that thesuper-orbital modulation in SMC X-1 is not caused by absorption in precessingwarped accretion disc alone and there are intrinsic changes in X-rays emanatingfrom the neutron star at different super-orbital states. We also note aputative cyclotron line at $\sim$ 50 keV in the \nustar~spectra of three brightstates indicating a possible magnetic field of $\sim$ 4.2 $\times$ 10$^{12}$ G.Finally, with the new pulse period measurements reported here, the time basefor the secular spin-up of SMC X-1 is increased by thirteen years and thecomplete pulse period history shows a sudden change in the spin-up trend around1995.

Is superorbital modulation in SMC X-1 caused by absorption in warped precessing accretion disc?