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Hard disk DMA mode is changed to PIO mode solution is how, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain in detail for you, people with this need can come to learn, I hope you can gain something.

As we all know, the hard drive must be turned on DMA mode to run fast. For the condition of turning on the DMA mode of various hardware devices, in addition to the motherboard BIOS must turn on the DMA support option, the IDE devices in the Windows operating system must also be set to the correct DMA mode. However, it is said that if Windows XP has multiple access errors (such as an abnormal shutdown after a crash), it will automatically lower the hard drive to a slower DMA mode or a slower PIO mode. How should this problem be found and solved?

In recent years, the hard drives produced roughly adopt several transmission modes, such as Ultra DMA 33 / 66 / 100 / 133 (at present, all hard drives above DMA100 are available on the market). The larger the number, the faster the data transmission speed. In general, Windows XP automatically sets it to the correct DMA mode according to the technical specifications of the hard drive itself.

However, according to a technical article published by Microsoft (http://support.microsoft.com/?kbid=817472)), when there are many errors in the XP system, the transmission mode of the hard drive is likely to be automatically modified by the system. If you find that the hard drive suddenly slows down, this may be the problem. Below, the author shows you how to force the DMA mode of the fixed hard drive to prevent the operating system from being modified, so as to keep your computer at its best.

1. First of all, how can we know whether the DMA mode of the hard disk has been modified by the XP system? Right-click the my computer icon on the desktop and click manage from the shortcut menu that appears.

2. After opening the "computer Management" window, click the "device Manager" of the left small window, and then expand the "IDE ATA/ATAPI Controller" of the right small window. Double-click the left mouse button on the "Primary IDE Channel" item, pop up the "Primary IDE Channel Properties" settings window, and then switch to the "Advanced Settings" tab to check the actual DMA mode in the XP system.

The columns "device 0" and "device 1" represent the first hardware device and the second hardware device connected by the IDE cable, respectively. Please identify according to the location of your hard drive. For example, the "device 0" in the author's computer is the hard disk and the "device 1" is the optical drive. If another IDE cable in your computer is connected to another hard drive, check the contents of the secondary IDE channel.

As for the codes in the "current transfer mode" column, they are: "mode 0 (DMA)", "mode 2 (DMA 33)", "mode 4 (DMA 66)", "mode 5 (DMA 100)" and "mode 6 (DMA 133)". Please compare yourself with the technical specifications of the computer hard drive.

3. If the system DMA mode shown in the above step is different from the actual specification of your hard disk, it may have been modified by the XP system. At this point, even if you change to the correct DMA mode in the "current transfer mode" column, the next boot will jump back to the original setting. Therefore, we must first switch to the "drivers" tab, click the "uninstall" button, and then restart the computer.

4. After rebooting, click "start" → "run" on the XP desktop, and type "regedit" to run the "Registry Editor" program. Then look for the following primary key: "HKEY_LOCAL_MACHINE\ SYSTEM\ CurrentControlSet\ Control\ Class\ {4D36E96A-E325-11CE-BFC1-08002BE10318}\ 0001"

5, after finding the primary key, right-click in the space in the right window of the Registry Editor, and click "New" → "DWORD value".

6. Rename this DWORD value to "ResetErrorCountersOnSuccess" (pay attention to case), then right-click the DWORD value and click "modify" in the shortcut menu that appears.

7. After the "Edit DWORD value" dialog box appears, change the "numerical data" column from "0" to "1", and then click the "OK" button. After rebooting the computer, the system can now be forced to change back to DMA mode that conforms to the technical specifications of the hard drive.

8. It is important to add that if your computer contains more than two IDE controllers (with more than two hard drives), there may be "0002" and "0003" under the "HKEY_LOCAL_MACHINE\ SYSTEM\ CurrentControlSet\ Control\ Class\ {4D36E96A-E325-11CE-BFC1-08002BE10318}" primary key. And other sub-items, representing each group of primary and secondary IDE channels, please modify them in the same way.

Similarly, you can also refer to Microsoft's technical article http://support.microsoft.com/?kbid=817472, to solve this kind of problem. The machine I played with appeared this kind of problem a long time ago, suffering from not knowing where to start to solve it. Sometimes I have to install a system every two days, and I dare not install other software. I always think that it is caused by installing some software. In the end, this is not the case. So I found this article, and now I am using this method, hoping to solve the problem.

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