While AMD is yet to announce the Ryzen 9 4900H, more evidence of its existence has appeared online. Sporting a 45 W TDP, 8 cores and a 4.4 GHz boost clock, the Ryzen 9 4900H should have enough reserves to challenge whatever Intel and its Comet Lake-H series has to offer. Its Radeon RX Vega 8 integrated GPU may even challenge dedicated GPUs, too, thanks to its 8 compute units (CU) and its 1,750 MHz boost clock.
https://www.notebookcheck.net/Evidence-of-AMD-Ryzen-9-4900H-appears-on-3DMark-with-a-4-4-GHz-boost-clock-and-an-RX-Vega-8-GPU.456558.0.html