As crossg noted, the 716 should be Master.
I ran the test you suggested. The graph has a straight green line with a decreasing yellow line underneath. I posted the results here:
Thanks, that tells a lot - that is not a normal-looking CD scan, something is locking the read speed at about 13x when it should be gradually increasing to 48x (see my scan below).
Things to look for:
- Px716a should be Master device on its IDE channel
- crossg's suggestion to select max speed in CDSpeed options
- Check the manual and locate the DMA jumper on the back of the drive. If a jumper is in place, remove it (power off first, of course).
- Run Plextools and under Drive Settings|Advanced, make sure the "Enable DMA" box is checked.
If none of that works, leave all those settings in place and disconnect the CD unit, thus leaving the Px716a alone on the IDE channel.
PS. In Plextools, Drive Settings|Basic, CD read speed setting should be "20-48x CAV"