The two rad fans look very skinny to me, especially when compared to the thickness of the rad. They do not look like stock fans of the EK-AIO 240 to me. Stock fans are 25mm thick. Yours look like 12-15mm slim fans. If so, they are unlikely to have enough static pressure to push enough air through the fins.
Edit:- check the spec of the rad for fpi. I imagine, AIO rad usually does not have too high or too low fpi but rather middle of the pack. Even so, I doubt slim fans would have enough power to push air through.
BS, the noctua slim fans on the EK rad are more than fine, running my formd T1 with this setup on a 3950x along side my 6900XT on air with no temp issues like the OP,my max fan speed is also set to 70% on the rad as i hate noise.
OP looks to be running one slim noctua and one stock EK fan anyway now.
In your photos you have it upside down, I am going to assume you are not running your tests like this?
As for Rad setup, I went fans on the case side of the rad pulling air through the rad and out the case, this gave me the best results, albeit harder to get the rad into the case.
you may just have lost the silicone lottery aswell, that is a possibility that you got a hot chip, i had this with my R7 1700s, in identical systems one always ran around 8deg hotter than the other for the same workloads at the same time, tried changing coolers out and swapping them over, that one always ran hotter.
I would tweak the voltages till you are happy with max temps under a full load extended stress test, then go up a smidge as you will not likely be hitting 100% cpu load anyway, given your build doesn't seem workstation focused like mine, then run a gaming load and see how much head up you get from the gpu pumping air into the rad.
other option as others said, you could make the fans intake, this will remove the gpu hot air type issues.
my 2c anyways.