jhm – Sun, 2004 – 12 – 26 09:51

My HP pavilion xf255 came factory installed with Windows XP and some software. To playback DVDs there ist the Intervideo DVD player. Whenever I played a DVD, my computer would regress into long bouts of disk access and audio stuttering. Booting was taking forever. In short, the laptop was unusable. And I blamed the laptop.

I also have Linux Mandrake 9.0 installed on the very same laptop, and appart from other shortcomings, the machine performed just fine, so I knew it wasn't anything hardware related.

screenshotOne thing I noticed under Windows XP was, that disk activity was slowing down my computer. This was especially apparent during audio playback. I know that my chipset supports DMA (Direct Memory Access), so I looked at the Advanced Driver Settings of my harddisk and discovered that it was not in DMA mode, and couldn't be put into DMA mode either.

I started googling for DMA and PIO and found this discussion. A Microsoft website confirmed what they were talking about in the dicussion:

For repeated DMA errors. Windows XP will turn off DMA mode for a device after encountering certain errors during data transfer operations. If more that six DMA transfer timeouts occur, Windows will turn off DMA and use only PIO mode on that device.

screenshotAccording to the discussion I had to change a certain value in the registry that controls what transfer modes a particular device can have.