I have a Xigmatek HDT-1283 cooler on an intel Q6600
the cooler is tall with a fan on the side.
with the way i installed it, the heat sink was to be positioned to allow the fan to blow straight up through a vent directly above it on the top of my case.
My thinking was that since hot air rises, and there is a vent perfectly placed there, this must be the ideal setup.
however ive realized that i installed the fan to blow downwards through the heat sink...
technically you'd be right if the air wasn't moving so fast in pc cases. also depends on your case and where the fans are. i keep mine facing the back.
i have the same cooler in my NZXT tempest.
and i was debating where the aim that damn fan hahaha.
ended up putting it towards the back and installing 2 sycthe slipstream fans instead of the zigmatek default fan. because of the 2 sythe sflex fans i use for intake that put in so much air omg my q9300 is hella cool.
I agree with it either pointing upwards or shooting out the back. I have a cheap aspire xplorer case with 2x80mm in the front, 1x80mm on the top as an exhaust and a 120mm fan as the rear exhaust. My heatsink shoots the air directly towards my 120mm fan and out the back. Plus with my psu on top of everything, it too sucks the air that comes out the cpu cooler. I guess that's why I get great temps when I oc with this bad boy! (below 60C at full load on an e6400)