ATA speed problem

Hello,
I've come across with the following on my PC: On my secondary IDE channel
I've set a DVD reader as slave device and a DVD recorder as master device.
The thing is that transferring data from the DVD recorder to the hard disk
is much faster that doing it from the reader, even though the DVD reader
read-speed specification is higher than the recorder's. DVD recorder uses
Ultra DMA Mode 4 transfer mode while DVD reader uses Ultra DMA 2, but that
should not justify the enormous difference in speed, I think.
I use an 80-wire cable.

Thanks,
Pedro