Hell if I know, I don't make the things
. I know my main PC does it (Gigabyte X58A-UD7 motherboard), and it seems to be common with various Dell models. I just tried copying an Ubuntu CD to my SSD, and the light was solid on, as was the one on the DVD drive. According to Windows, my SSD was sitting at 0-2% utilization (mostly 0). If I play an audio CD, both LEDs flash in tandem.
I don't know exactly what PowerDVD does, as I've never used it.