This is what you do. Go into mobo uefi and check that both the gpus are being read in the bios. Once that checks out than make sure that there isnt some setting preventing from them working together. such as lucid vmp will sometimes do
Dude that if more than a fine temperature under idle and under load. Download real temp it should support your cpu.
You can run your fans lower if you wanted. My 8150 went to around 80c on air cooling when it was overclocked so I think that the 9590 will be fine on water with 60c. Remember a true test is atleast an hour on prime to ensure that the cooler will keep with long term usage.