Plextor Burn Problems

I'm seeing very poor performance when burning a DVD from my RAID-0 with a Plextor PX708A. I have the most updated firmware on the drive and the media I'm using is the same. The buffer in Nero goes crazy. Burn which should take 7-8m takes @14m.

BUT if I burn a DVD from my RAID1 set, it is perfect.
I'm going to try burning a DVD with the DVR108 to see if it's the IO.

Can someone explain why this is the case?

If it's IDE I can try.

Go in to Device Manager and go to the
IDE ATA/ATAPI controllers option, and expand it. Right click on the channel your burner is on. Go to properties.
Advanced settings.
Make sure both Device 0 and Device 1 are set to DMA if Available NOT P10 ONLY.

Do this again for the other channel, just in case.

Both Primary and Secondary are already setup in this fashion.