Your thermal paste spread was actually perfect. The spread is supposed to be extremely thin, and the transparent areas are that of perfect contact which ideally should be in the middle. And yours was. What speed is the pump running at? If it's hooked up to the motherboard it is possible that the BIOS is controlling the pump speed (based on CPU temp) and this slowing it down when system is idle. If that is the case you can modify this setting through BIOS or your motherboard software. Tilt the case just under 45 degrees on either side while the system is running - it's possible an air bubble is stuck somewhere also. Saw it happen a few times on my h100 after I moved the system around, had a bubble stuck in the pump. I heard it go up the hose when I tilted the case towards me.
Pump speed Max is 2600-2800RPM on that unit.
thank you, Scorpion667, it didn't occur to me that i might have an air bubble in the pump. Will try to "burp" it :P