The limit of conventional X-ray powder diffraction for the detection of supported nanoparticles is usually taken to be 2-2.5 nm, at which size low signal to noise ratios make detection of particles of low weight loading and small particle size difficult. State of the art silicon strip detectors, however, are 2 orders of magnitude more sensitive than scintillation counters, and the greatly improved signal to noise ratio obtained in typical powder XRD scan times (tens of minutes to several hours) allows for the detection of much smaller nanoparticles than was previously possible. In this paper we demonstrate the use of a Si slit detector to characterize Au particles supported on carbon at sizes as small as 1.2 nm and weight loading as low as 0.33 %. At elevated scan speeds good corroboration between STEM and XRD is maintained. Thus, the latest generation XRD detector allows quick and simple access to the behaviorally rich 1-2 nm particle size range.