Should be easily obtainable if your mobo will allow you to OC, which it should unless this was a pre-built. Off hand I think the max OC's people were getting from these CPU's were 3.2-3.4ghz in OCs but they were mostly using the e2140's big brother the e2160. Identical CPU but slightly higher multiplier.
I personally used a e2180 for a 3ghz OC and barely touch the voltage which was my goal of getting the highest obtainable clock speed without pushing too much voltage into it. To get any higher I had to bump it up to around 1.4v+ or so compared to the 3ghz OC which was in the 1.1v-1.2v range I can't remember specifically.