Energy-dispersive X-ray spectrometry (EDS) is a key analytical tool aiding root cause determination in the failure analysis (FA) process. This paper looks at a number of analytical TEM microscopes currently in use in various facilities: microscope A, a STEM operated at 200kV; microscope B, a 300kV TEM; and microscopes C and D, both 200kV TEMs. EDS counts per unit time from multiple microscope platforms were examined. Microscope D demonstrated two orders of magnitude higher counts per unit time than the other three microscopes. Microscope D represents the state-of-the-art EDS analytical TEM configuration and has achieved this through a novel windowless EDS configuration which significantly increases the detector area (by about a factor of three) that receives X-rays generated from the sample.