Good news! You'll appreciate the noisy fan when your 250EX doesn't blow it's guts out the back after a couple years. Also it makes an awesome gas saver: get in the habit of turning off the gas bottle valve when you turn off the welder.
Fun fact: There's a part used in practically all electronic devices which has a very finite lifespan. The part's lifespan decreases by a factor of 2 for each 10degC rise in temperature. And if the welder isn't on, the part will be significantly cooler.