I am thinking that your CPU temps should be about 5°C lower - but then, I don't know what your voltages are at.
I have an i5-2500k under a NH-D14 and it idles at 17°C @1.6gHz @ .972v,
with 41°C @ 4.4gHz @ 1.284v under full load for 7 hours.
Ambient air is 22°C.
If it were me, I would pull the Noctua if the temps don't drop in a week and apply a thinner layer of paste. You're using NH-1 right?
i don't think that, on air, your temps should be below ambient temperatures unless you introduce very nice cooling to the air around the computer making it colder than the rest of the room, obviously unreasonable since this would yield temps lower than phase change and more expensive
my volts are a little higher at load but i ran the test for 25 hrs the last time that i posted and at 1.285v mine gave me an error after about 11hrs (lol). a bump to 1.29v solved all errors.
i am actually using the DH- D14, like you. my temps have lowered a few degrees over the weeks because of curing
i am having hard drive troubles now.