The application of X-ray Diffraction Imaging to measure in operando thermal strains at individually powered components within fully packaged LM3046 silicon devices is described. It is shown that as the local strains increase with power dissipated, above a threshold power loading, the associated region of enhanced X-ray intensity increases monotonically. The changes in contrast in the image are discussed. Asterism in section topographs changes sign as the slit is moved across the component, consistent with lattice strain around the device due to the thermal expansion. Above a threshold power, this asterism increases linearly with power loading. By simultaneous measurement of the package surface temperature it is possible to deduce the local component temperature from the extent of the contrast in the X-ray image.