If your Mac goes bad it can be worthwile. My friend gave me his pre-Retina 27" iMac, part of the circa-2008 generation of Macs whose GPUs all failed.

I removed all the computing hardware but kept the Apple power supply, instead of using the cheapo one that came with the LCD driver board I bought. I was able to find the PWM specs for the panel, and installed a cheap PWM module with its own frequency & duty-cycle display to drive it and control brightness.

The result is my daily desktop monitor. Spent way too much time on it, but it works great!