I got my g15 with the 350 dollar discount back in June and it was an absolute steal. The difference between the 5900hx and the 5980hx is a 200mhz top end. My 5980hx will easily clock at 5ghz. It may help in gaming but I doubt it. What really helped is changing the memory to a 32gb 3200mhz x8 cl17 set. I went from 1080 single core to 1650 single core and 7600 multi core to 10050 multi in geekbench.
Before you jump at this, read this: https://www.notebookcheck.net/The-Asus-ROG-STRIX-G15-laptop-with-Radeon-RX-6800M-cannot-reach-its-true-gaming-potential-due-to-slower-stock-RAM-and-missing-MUX-switch.543110.0.html
In a notable deal for the Asus ROG Strix G15, a high-end all-AMD configuration featuring a quick octa-core processor and the quite capable Radeon RX 6800M is currently sold for just US$1,399 at Best Buy.