52c under load is pretty good. The main thing about water coolers, especially AIO watercoolers, is that you're not going to see a massive decrease in temps over your standard air cooler. As an example, my i5 2500k at stock settings was around 26 idle and 55 load with a hyper 212. When I added my H100i I was around 26 idle and 56 load.
Where they really shine is when you start to OC. my i5 2500k at 4.2 ghz was around 70 under load with they Hyper 212, but with the H100i and overclocked it would barely hit 60 during a stress test.
You're not going to see a huge improvement using a AIO watercooler on stock settings (although the better airflow in your case makes everything better), but when you start to OC you'll also start to see better...