Check your temps at full load when you are not overclocked..if its under 60 celsius proceed to overclock with stock cooler.. it's not only about overclocking but also the air ramming into the cpu from the cooler... if your pc is new there wouldn't be problems ,but if its full of dust do not even try overclocking anything...Clean the whole system and apply new thermal paste over cpu just to be 100% sure about NOT frying your cpu...
Now the overclock part...
Your chip is safe with stock cooler in the 0.8500V-V1.3625 voltage range by factory
that means you can up your true voltage up to 1.3625..check readings from cpu-z its the true voltage
I never overclocked with such a chip ,im running with my e4500@2.2 ghz at an overclock of @2.6 ever since 2009 24/7 and haven't had stability problems after some final settings done through BIOS
Your mobo as i can see through google,is just a single atx,without overclocking capabilities..
this means that it can't overpower the cpu with your bios..which also means you should buy an aftermarket mobo to overclock with hardware...
There is the solution to software overclock but you shouldn't use stuff like that on a motherboard that is not designed to overpass standar voltages and frequencies .
Apart from that, just to let you know,the core 2 duo e series are designed to run steady on the next level of e with overclock...im trying to say that your 2.93 can reach 3.07 without effort,but is a sad overclock not worthing at all..
You can off course overpass 3.40 ghz in my opinion with increases in voltage,but as i told you...only with a mobo designed to overclock...
Anyways good luck in whatever decision you will make