I had a Richo MP5240A as my Burner and the Lite-On SOHD-167T as my reader. I had no problems burning at 4x as the burner did burn at 4x max.
I have since purchased a Pioneer 108 16x DVD burner and have not got the issue that I can only burn at 4x and at times 2.4x. When I use Ritek 4x +R media it burns at 2.4 times and when I used a Ritek 8x -R it burnt a@ 4x.
I am using Nero and I used the NERO utility to check the drive speed of my Lite-On SOHD-167T and it give a reading of about 5.7X
The firmware for the Lite-On SOHD-167T was 9S15 and now I have upgrade to 9S16.
Can someone out there help me.