how cool does a Asetek 510LC Liquid Cooling System 120MM Radiator & Fan keep a fx 8350

The Hyper 212 Evo is a great cooler and should cool your chip just fine. If you want to go to the edge with an overclock, at least an AIO H2O kit is in order. I have used Aseteck parts in custom loops and they make good stuff. Although I use single wide rads with dual fan setups nowadays. Custom loops cool great, but they are too much work in my mind (and very expensive). If you have room, go with a 240 size rad with quad fans in push pull. That will work very well. If you only have room for a 120 size kit, I recommend any of them that is on sale with the thicker radiator (I got my Zalman 520 for 43 bucks!) Corsiar's kits are very good too. Sorry, lots of words, but hopefully it helps.