Abit AX5 Instruction Booklet page 94

E-2
The higher the MODE value is, the best is the hard disk data transfer rate.
But this does not mean that you can select the highest mode value as you like.
You must be sure that your hard disk supports that type of fast data transfer,
otherwise your hard disk will not be able to operate correctly.
Here are some examples of data transfer rates for IDE HDD with DMA
mode:
DMA Mode 0 The fastest data transfer rate reaches 4.16Mbyte/sec
DMA Mode 1 The fastest data transfer rate reaches 13.3Mbyte/sec
DMA Mode 2 The fastest data transfer rate reaches 16.6Mbyte/sec
Usually, PIO mode means that the hard disk data are accessed by the CPU
through the chipset and placed into memory, and the chipset is using PIO mode
to access hard disk data.
MASTER mode means that hard disk data are accessed by the chipset, and
that the chipset places the data into memory. The chipset is using DMA or PIO
mode to access data stored in the hard disk drive. The Master mode can reduce
the CPU load, especially in a Multi-task environment. This can help system
performance.
Appendix E