If you genuinely want an answer, take a picture of your CPU cooler for us to see. Dell has many desktops with this CPU. They may use different coolers, so we can't provide an accurate answer. One thing is for sure, an OEM isn't going to use the Intel stock cooler for boxed CPUs.
Still, an i5 3330 isn't going to produce much heat, so as long as you aren't stressing the CPU, you should be fine with what you have. A new CPU cooler may cause problems in an OEM PC, which may have proprietary mounting mechanisms and/or clearance requirements.