Not the fan is the problem, which is 92mm/92mm, but the dell proprietary coupling on the motherboard which is not standard like any other. So if you don't have soldering knowledge and change the wires from the old one to the new one, i'm afraid you will have to buy an original fan. Other option is ebay, i have seen some replica fan there with dell coupling.
You will need a fan with about 60 cfm, keeping in mind that the cooler on the processor is passive and the fan is mounted on the case. the maximum wattage of processor for this model is 80w, so 60 cfm is more than enough.