I'm assuming you are possibly a little new to overclocking and if not I apologize for the assumption, but anyways yeah it looks like a decent cooler, but there are also many things to keep in mind, especially if you want to overclock. When I got my 8120, I went ahead and got a cheap little closed-loop water-cooled system for about $60 (Antec H20 620), because I finally wanted to get my feet wet, so to speak. While today's air coolers are a hell of a lot more advanced than they were 5-10 years ago, they still don't dissipate heat as effectively as water cooling. It seems like most people are getting comfortable around 4.5 GHz on the 8120's, at least for a 24/7 OC. When this CPU hits about 4.3GHz+, the curve at which you have to increase voltages starts getting a little out of control (4.6-4.8GHz), and on air, people seem to be a little squirmish around these clocks, and for good reason. The typical TJmax temp on an 8120 seems to be about 70c (some are even 90c), while AMD only guarantees it to work up to 61c
. My point is, the people I know that have air cooling on this cpu are already kicking themselves for not going with a watercooled system. Overclocking can be very addictive, and it would suck to hit 4.5GHz, and wonder how much higher you could have gone had you went with water cooling in the first place. My buddy's 24/7 OC on air is 4.5 at about 50c under full load. My 24/7 OC is 4.7 and just under 50c at full load. He couldn't ever go higher than 4.7 without scaring himself half to death. When I got to 4.8, it wasn't very scary at all, so of course... I had to hit 5GHz. I couldn't get it stable, but my temps were still within range at 5GHz. That's the overclocking downside to air cooling.
Another thing he didn't like is how his case is windowed, but when you look inside most of what you see is this big, bulky chunk of metal, and blocks all of the lights from his cold cathodes, plus after he heard mine, he said he couldn't even tell it was on it was so freaking quiet. In fact, when I installed my water-cooler, I was afraid it wasn't working because I couldn't 'hear' anything to prove it!
A lot of people fear water cooling because they picture a hose bursting and water going all over the place. On the 8120, it shouldn't be an issue with the TJmax being as much as 40 degrees less than some intel's who sit at 100c in some cases. My point is, unless you are going to be overclocking above your TJmax (which you should never do) today's double-oring sealed water coolers should be more than enough to handle it.
In conclusion, while the Zalman will certainly get the job done, is it what you really want?