Who best dma or pio mode

DMA is newer and better. The exact technical differences? That's what Google is for.

DMA has lower CPU overhead and transfer rate is much faster. A few years ago one of my hard drives switched from DMA to PIO mode for some strange reason. When it was in PIO and I was trying to move a somewhat large file, say 50MB, Windows gave me an estimate of like 10 minutes to transfer the file from one hard drive to another. I also noticed my PC became somewhat sluggish.

It look a bit of snooping around to notice the mode switch. Needless to say, I switch the drive back to DMA mode, rebooted and all was fine again.
 
PIO is defintely way too slow. You would notice the difference if you are copying CD/DVD to you hard disk. If your CD/DVD Drive is set to PIO mode and you are copying a large amount of data from it. You may get an estimate of more than 40 mins for 700MB or something.
 

hairystuff

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From experience I have found that PIO is good when the system is running unstable normally due to dodgy ram or data recovery sessions, although it is a slower mode I have found it more reliable during maintanence and recovery.