How about for 4K Gaming, will it keep the temperature at an acceptable rate
4k gaming will put more stress on the GPU, CPU load will barely change. you will be good to run it at 4.3-4.4Ghz and be lucky to top 70°c in stress tests
While using the feature of 4K gaming will the cooler stay silent
the pump on the H90 is extremely quiet, the fan on the other hand can get a little loud if its cranked up to 100%, you can always buy some after market fans for the cooler to achieve a quieter profile
Seen as my computer case can only fit up to 185mm cooler is the h90 the best option I can get for performance/price
watercoolers generally perform better than air coolers when it comes to cooling/size. a H90 would cool the same as if not a littel worse than a noctua NH-D14 which is a massive dual tower air cooler. watercooling also has the added bonus of removing the hot air strait out the back of the case