The Sandia National Laboratories SPHINX accelerator is used to study the response of electronics to pulsed x-ray and electron environments. The system consists of a Marx generator and an oil-insulated pulse-forming line with self-closing oil switches. SPHINX has a peak load voltage of 2 MV and an adjustable pulse width ranging from 3 to 10 ns. The previous pulsed-power system had reliability and triggering issues with the Marx generator and subsequent undesired variations in voltage output. SPHINX was upgraded to a new Marx-generator system that has solved many of the voltage-output fluctuation and timing issues. The new Marx generator uses recently developed low-inductance 100-kV capacitors and 200-kV spark-gap switches. This paper provides an overview of SPHINX while capturing in detail the design, characterization, and comparative performance of the new Marx generator.