not going to sli, It will be more for storage and I dont plan on over clocking much more than 4.2ghz with the 3570k i bought with it. Its going to run a surveillance system, cs6, visual studio 2008, v-machine running linux. maybe a minecraft server.
I have the Pro 3 and I overclock the 2500k to 4.2GHz with no problem. I'm not sure how your usage will be affected by your choice of motherboard. I would recommend the Extreme 4 because it is a good improvement in build quality, although it's really for people who want higher CPU overclocks or SLI.