I purchased an IQ2 and IQC, and while these devices are very well designed, precise with temperature control and vapor production, I was disappointed with the IQC's "buzzing noise" it makes when desired temperature is reached. I've compared it to the IQ2 and I can barely hear anything compared to the IQC. The feedback I received was due to the pulse width modulation (PWM) which makes sense that at desired temperature it has to increase the resistance, however the IQ2 doesn't emit nearly the same level of "buzzing noise". I don't recall the noise being there from the first couples of uses and now seems as if it has increased over time. I now can't stop hearing it...wish I had an option to trade this unit for another.