That is a bit high for just a cpu loop using the equivalent of 360mm of Rads. I've a few questions though; What Rads, pump and fans are you using? What speed are your fans set at? When's the last time you flushed and cleaned your system. Your system specs would be really helpful.
What program do you use to monitor your temps? Is that 55 Celcius across all four cores? Those sound like the temps I got when using just a Corsair H100. And that's a 240mm rad with stock fans running Prime 95.