It has been confirmed that it was one of AMD's new Matisse desktop processors that smashed its way through Geekbench's multi-core test recently; more precisely it was a Ryzen 9 3950X engineering sample (ES). Apparently, the system featured an overclocked CPU utilizing an AIO water cooler and an X470 reference motherboard.
https://www.notebookcheck.net/AMD-Ryzen-9-3950X-ES-confirmed-as-Geekbench-wrecking-record-breaker.424798.0.html