CCFL can also use PWM, and the icing on the cake is that very often their PSU emits a buzzing noise when it's not running at full capacity.
It's all explained in that link really:
PWM on LED Monitors can cause headaches due to flicker
Quote:
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How PWM works on a LCD monitor with CCFL and on a LCD monitor with LED. Notice the significant light fluctuations. These fluctuations can cause eye strain
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The first 46" Hitachi TV set I tried was using CCFL, its PSU was buzzing and I was seeing agressive light green RBE's on high contrast movements. But no headaches this time, prolly because the response time of CCFL is slower than LED's.
Eizo have been selling non-PWM monitors for a while and they even have an old VA model currently selling for relatively cheap but its overdrive is extremely poor apparently.