What kind of issues are you having?
I find it hard to believe that with your amount of airflow the simple change of a heatsink could affect your system like that
Random lockups, failing LinX with lower temps and identical voltage settings that were passing with higher temps. Restarting LinX and suddenly passing after just failing. Really weird and random crap.
The NH-D14 is so big it just blocks most of the airflow to the components below it.
When you used the Delta fans, did you see an improvement in temps? I have thought about buying some higher rpm fans like the Delta's for my NH-D14 but if you did not see much of an improvement, then I probably will not.
No the Delta's don't supply a good airflow to the center heatpipes plus their extremely loud.
That's another problem with the NH-D14, even a regular fan has a dead zone in the middle so the heatpipes located in the middle sections of the fins don't get cooled as well as the outer heatpipes. They should move the inner heatpipes outward about 1/2" to an inch.
But all is good again as my trusty TRUE Copper is back in action