Just saw BIOS update 310 come through MyASUS. This is probably the quickest back-to-back BIOS updates I've seen in a while, only arriving a couple weeks after BIOS 309, so my guess is they were in a hurry to fix or change something. If anyone notices any changes after updating, please report it here! I will try to do the same.

EDIT:
UPDATE: Did some testing throughout the day running benchmarks. Personally I can't find a difference between BIOS 309 and 310 but what I did find that I didn't realize was that both 309 and 310 completely demolish Silent mode. I'm talking less than half the performance in Silent mode at around the same fan noise, great job Asus. I could get about 13-14k graphics score in Time Spy (incredible btw) in Silent mode on BIOS 306, but now it's about 5-6k.

So it seems that they lowered the GPU throttle level to 70C. I tried to use G-Helper to get around this but unfortunately the bios update bakes it in. And it throttles HARD. From 85w to 55w but the GPU memory drops even further, resulting in Time Spy going from 100 fps to like 34 fps throughout the run. On Bios 306, it only lightly throttles around 75-80C and only down to about 70w but still maintains great performance. If you disable cpu boost in silent mode, you get even better performance as the GPU is able to run much more stable with better thermal headroom. Disabling boost is also super easy now thanks to G-Helper.

Another difference is the fan curve is actually more aggressive on 310 at least for me. I only opened two tabs in Edge and the fans kicked in. Tested it a few times and only took very few actions before fans would turn on in Silent mode, which is quite the opposite of normal Asus ROG laptop behavior. Downgraded to 306, and it took about 12 tabs, playing some videos, running updates, opening and closing Armoury Crate and MyAsus before fans even kicked in a little bit and then quickly went back down to 0 rpm. Like come on. That's the good stuff that we like Asus, why would you ruin that, lol.

So I'd recommend using Asus EZ Flash to downgrade your BIOS to 306 if you weren't having issues with that one. It's very easy to downgrade the BIOS, but you will have to disable Asus' update service to prevent it from auto-installing the new one when you reboot again. Super annoying that it does that.