Noctua NH-D14 air cooled here too and I've been running extreme overclocked for 2+ years with no heat issues (3.3Ghz running at 4.8Ghz).
This NH-D14 replaced a faulty Corsair H100 watercooler and it has been just as cool within a couple of degrees but much quieter, great air cooler.
As far as FSX Out Of Memory issues, I recommend checking on AVSIM or the FSDreamTeam site, there is a known problem with FSX when running some combinations of stacked high detail add-ons of region + airplane + airport, i.e. ORBX + 737NGX + FSDT KLAX or FSDT CYVR and the limitations of FSX being a 32bit app and all those details exceeding it's available memory on approach once FSX has to display the airport detail. Search for "OOM" on those sites.
I remember reading details there on how to diagnose the problem by checking how much memory FSX has in use before the crash and also some ideas to try to avoid it, I think FSDT provided lower res texture and detail options for the airports to help customers avoid the condition.