Overclocking computer?

ok im wondering what would be a safe(ish) amount to overclock my processor its at 2.1 and want to know what it can go up to its a micro atx motherboard if it makes a difference and manufacturer was acer and am going to go up to 3.2 thats impossible im not going to do it until i get a new case as its the x3200 with is very compact and it will most like to overheat ive never had any problems with it overheat as of today