We present the variability analysis of a 100 ks XMM-Newton  observation of the Seyfert 1.5 active galaxy NGC 3227 .
The observation found NGC 3227 in a period where its hard power-law component displayed remarkably little long-term variability .
This lucky event allows us to observe clearly a soft spectral component undergoing a large-amplitude but slow flux variation .
Using combined spectral and timing analysis we isolate two independent variable continuum components and characterize their behavior as a function of timescale .
Rapid and coherent variations throughout the 0.2-10 keV band reveal a spectrally hard ( photon index \Gamma \sim 1.7 - 1.8 ) power law , dominating the observed variability on timescales of 30 ks and shorter .
Another component produces coherent fluctuations in 0.2–2 keV range and is much softer ( \Gamma \sim 3 ) ; it dominates the observed variability on timescales greater than 30 ks .
Both components are viewed through the same absorbers identified in the time-averaged spectrum .

The combined spectral and timing analysis breaks the degeneracy between models for the soft excess : it is consistent with a power-law or thermal Comptonized component , but not with a blackbody or an ionized reflection component .
We demonstrate that the rapid variability in NGC 3227 is intrinsic to continuum-emitting components and is not an effect of variable absorption .