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Slow computer, High CPU utilization, the stuttering DVD drive or the lame hard disk?

September 28, 2008 21:36 by Aleksandar

Do you experience: 

  • Suddenly very slow computer
  • Constant high CPU utilization during file transfer
  • Lame hard disk performance
  • The stuttering DVD drive
  • Choppy DVD playback
  • Your drive is always in PIO mode and you can’t set it to UDMA mode

If you have one of these problems most probably your drive has switches from UDMA to PIO mode.

What does it mean?

DMA is an abbreviation for Direct Memory Access, an access method for external devices where the data transfer is not done by the central processor, but by a small special processor called DMA controller. It uses a procedure called cycle stealing, where the central processor memory access cycles are delayed for very short times to intersperse DMA controller memory access cycles. Some newer, faster DMA modes are called UDMA (Ultra DMA).

The alternative, slow and inefficient data transfer mode is called PIO, Programmed Input-Output, where the central processor transfers data byte for byte or word for word. This requires many processor commands for each data word and therefore causes a high and unwanted processor load.

Solution is here:
1) Download the file from here: http://winhlp.com/tools/resetdma.vbs

2) Despite any warnings click on the [Open] or [Execute] buttons as required to execute the file resetdma.vbs. If you fear to download the file, you can use the manual method instead (see link below). Or you could download, save, and inspect the program with an editor like the Windows Notepad. It is a script text file.

3) If the program found any ATA channel to reset, reboot your computer and test all drives.

4) If the problem is still not solved, set the offending channel to PIO manually, reboot your computer, set the channel back to DMA, and reboot again.

5) Please report your results here http://winhlp.com/node/97.

For more technical background or menual method visit this site:
http://winhlp.com/node/10


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Categories: Hardware | Windows
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