It looks to me like the A4-H2O case is designed so that the AIO fans pull air up over the motherboard. Raising the minimum speed of them should help pull heat away from the chipset heatsink. I'd probably start by adjusting the fan curves to 50% minimum, 100% at something like 75 or 80C on the CPU, then play with the middle of the curve to find a good ramp for them. If you need extra airflow, the Noctua A12x25 (that's the new next gen one with the curved blades, similar to the Strix GPU fans) is worth a look, along with the rubber radiator gaskets for it.
The Z690 chipset does have a reputation for being a bit toasty. Try disabling onboard devices that you don't use, in the BIOS, that's supposed to help. I'm on X570S, so can't remember exactly which chipset devices were the particularly hot ones on Z690, just have read reports that it helps in some cases.