Use Realtemp to monitor your CPU real tempurature
http://www.techpowerup.com/realtemp/
On my own 3570k I have a Cooler Master Storm Trooper Case and the Corsair H100 cooler. I also bought aftermarket Liquid Pro
http://www.coollaboratory.com/en/products/liquid-pro/
At 43 multiplier and 103.00 FBS I am at ~4430 Mhz and 1.32v.
With those cooling solutions I hit about 55 Celsius after hours of Prime95.
With your cooling solutions, I think you are right where you ought to be.
To clarify, 105 is the maximum tempurature for the Ivy Bridge i5 3570k, but that is a maximum, not a threshold. Most overclockers prefer to stay under 90, if you are hitting 65 from 100% cpu stress at stock settings, you are under the maximum. Increase your overclock by 100 Mhz at a time, or 1 multiplier, run Prime and Realtemp, once you start hitting 75-80, consider that your maximum, as I'm sure you would like to keep your CPU alive for a long time. Also, pay close attention to your voltage, anything over 1.35 is considered highly dangerous for the cpu at long stress times. Although Intel says that 105 degrees and 1.52volts are the maximums, those numbers should never be used for a day to day use machine as they burn out the cpu quickly.