As someone posted, limit threads (-t). Easy way: Subtract one from how many cores you have, all i3's that I know of have 2 cores, so you can do -t 1, but your hashrate will be horrible. Better to get a temperature tracker like RealTemp or SpeedFan  and play around with -t. I can do -t 10 on a quad core and keep temps low with good circulation, just as long as temps are down, you're fine.