Why would hard drive keep getting switched to PIO mode in XP? [Archive]

Sulik

27th June 2004, 08:13

Sounds like you should get a new hard drive before it's too late.
XP will automatically switch to PIO if there are read/write i/o errors in DMA mode.

Did you check your event log ?

Sometimes these errors could be due to corruption at the bus level, due to a bad PCI device or incompatibility between 2 devices (in case you recently installed something).

Angelus

27th June 2004, 12:56

Not sure if this really helps but it explains I think what you are experiencing:
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.

In this case, the user cannot turn on DMA for this device. The only option for the user who wants to enable DMA mode is to uninstall and reinstall the device.

Windows XP downgrades the Ultra DMA transfer mode after receiving more than six CRC errors. Whenever possible, the operating system will step down one UDMA mode at a time (from UDMA mode 4 to UDMA mode 3, and so on).

If the mini-IDE driver for the device does not support stepping down transfer modes, or if the device is running UDMA mode 0, Windows XP will step down to PIO mode after encountering six or more CRC errors. In this case, a system reboot should restore the original DMA mode settings.

All CRC and timeout errors are logged in the system event log. These types of errors could be caused by improper mounting or improper cabling (for example, 40-pin instead of 80-pin cable). Or such errors could indicate imminent hardware failure, for example, in a hard drive or chipset.

Source:
http://www.microsoft.com/whdc/device/storage/IDE-DMA.mspx

Actually just found another good site too explaining one occurence and a fix for it:
http://www.mcse.ms/archive57-2004-2-44740.html