No that makes a lot of sense. I always steer clear of the Dominator RAM (for this very reason), I prefer the XMS3. But still, I wouldn't expect it to make a huge difference from the fan being elevated slightly.
Heh - LW_Black4 is right, check the fan is connected to the correct header on the motherboard. Check your BIOS settings and ramp up the onboard fan controller speed as much as possible.
Failing that, in some cases (for butch overclocks and such) I have just connected my CPU fan directly to the PSU using a molex-to-3pin-fan adapter. This way the fan is just locked at 100% speed.
I reckon it is worth making sure the cooler is properly attached to the motherboard. And a good thermal paste is used. And the plastic film was peeled off the bottom of the heatsink (obvious, I know)