Cooler for 720BE + AM3 board

[rvilkman]

What would be a good air cooler for OC:ing the 720 BE?

MB will be either
Asus M4A79T Deluxe
or
MSI 790FX-GD70

Case will most likely be a Lian-Li PC-7BYCF.

From what I've been reading most of the bigger coolers block off the memory slots for these AM3 mb's. Is there some kind of a nice solution which would be efficient, hopefully easy to install and wouldn't block the slots?

Xigmatek Black knight
or
Xigmatek HDT-S1283

Seem to be good choices in efficiency and bang for buck, I have some concerns about fitting them into the case & MB

Also taking in recommendations for thermal grease or should i simply go with Arctic Silver 5?

 

[AKM880]

Those both are nice coolers, also take alook at the Scythe Mugen II cooler. OCZ FreeZe works good for thermal paste 😀