I had this same problem a couple days ago on a reformat.
Fist thing my bios was listing my Sata set as dma. Windows listed as pio.
When i looked at my Channels the sata was listed under the Ide Channels.
The way I fixed mine was to Install the latest chipset driver and then i instaled the Sata/Raid Driver for my MoBo. It put the Sata under SCSI/Raid Channel in The device manager and that fixed my problem.
Was nothing Wrong with the burner and that was set to DMA all Along. The problem was that my sata was in pio and caused the slow burnings because the images were held on my sata.
(My drive is the LH-18A1P)
Heres My post on my problem.(seems u have the same thing happening)