@3.5GHz I started getting too many hangups and bsod's, (mostly because the psu is a cheap p.o.s. I suspect)
but they became once then twice a session and it interfered with my WoW duties so I backed it down to 3.4 for a while, then settled at 3.2Ghz,
Al in one liquid coolers are a touchy subject hehe, the really bad ones are worse than aircoolers, and even the best ones can be beaten by good air coolers, a lot of the overall situation still depends on your cases airflow set up, which ever you opt for, but good air often beats bad water
as mentioned, any mobo with a 710 or higher chipset will support acc, mine was an asrock m3a770de, nice plate and cheap as anything now too, but if budget allows, get a higher model ofc (Lol, just...