Quite honestly, they’re both equally risky. When it comes to liquid CPU coolers, you always have a chance that something malfunctioned or being damaged right out of the box. Of course, if it leaks, your PC will be dead in the water. Don’t start thinking you’re 100% safe with air based CPU coolers. If you happen to apply the thermal paste poorly/incorrectly, the cooler’s performance can drop to damaging levels. If the air based cooler is not seated properly, that’d be another potential big problem.