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On a brand new system (freshly installed) Burning CD’s and DVD’s in Windows 7 is a very fast and enjoyable experience. Then something happens, you suddenly experience that Windows 7 takes for ever to complete a burn session. Some have experienced it taking up to 2,5 hours to complete a DVD. Which would mean a transfer rate of about 370 kb pr. second. where about 4,500 kb pr. second  (15-17 minutes) is considered slow.

What happened ?

There can be a number of reasons, but what you experience might be that your computer (or the device controller) has switched from DMA-Mode to PIO-mode.

Say what?

I’d thought you’d say that. Before we get into how to fix it – let’s look into what DMA and PIO are.

  • DMA is short for “Direct Memory Access”
  • PIO stands for “Programmed Input/Output”

Ah, now you’re making sense – not really.

The difference between these two settings, is speed. A whole lot of speed. What DMA does is to sneak data past the CPU when it’s not paying attention. Sort of sneak past the door man at the club or concert you want to go to. This enables the burning device to flush data onto the media without having to process the data. The result is HIGH Speed data Transfer.

Using PIO-mode, means everything has to pass through “security” first (the CPU). And this makes things go really slow.

So … why do we have PIO?

The main reason is one of Microsoft’s favourite words: Compatibility. Not every device supports DMA. And not every DMA-ready device supports it a 100%. So, to keep your system ‘at go’ all the time. There is PIO.

But everything worked just fine – WHY did it switch?

Again, the answer to this can be so many. But one popular reason can be that you have tried to use “hard to read” disks or media. let’s say a very scratched DVD. Your Device Driver says something like: “Ok, this didn’t work. I can’t access this”, thinks something is wrong (with the device), and switch over to PIO-Mode. When that seems to work, it “Forgets” to reset back to DMA-Mode. – Without telling you about the decision – leaving you clueless as to why everything has slowed down to a crawl.

How and Where do I FIX this?

Ah, now comes the fun part. Note! This might not be the solution to your problem, yet it’s worth a try. First we need to find out which Channel your Device uses. Then we need to access the Property settings for that Channel. Here’s how:

  • Open The Device Manager.
    (Right Click on the Computer Icon (“My Computer”) and choose “Manage”. Then Click “Device Manager” in the left side menu.)
  • Locate your device under the “DVD/CD-ROM drives” tag. Right Click it and choose Properties.
  • In the General Tab, there’s an overview of the device, where one of the labels are: “Location”. Here you will find which Channel the device operates on. My device use Channel 0 (zero).
  • Now Open the IDE ATI/ATAPI Controller Tag
  • Right Click on the proper Channel (if more than one using the same number, choose the first one).
  • Click on The Advanced Settings Tab
  • If the DMA setting isn’t Checked, Enabled it
  • Click OK

About Thomas

Computer geek from the age of 7, which amounts to 30 years of computer experience. From the early days (when every computer company had their own OS) of DOS, Windows 1.0 through Seven...

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8 thoughts on “Speeding up my CD/DVD-ROM: What Are PIO and DMA, and How Do I Change Them?”

  1. akbarri says:

    correction @ “Say what?”

    “DMA” not “DMO”

  2. Anonymous says:

    I am a bit confused.
    ok so my optical drive is on Location 1.
    I open ‘ATA Channel ‘1 under ‘IDE ATA/ATAPI controllers’. Go to the “Advance tab”. From there I see, “Channel Properties” group, which contains only the following: “Supported Devices 1”
    Below there is a group called “Devices” with an empty data grid, and bellow that I have “Device Properties” group and it’s empty.

    But then again, I don’t have the problem, and my optical drive is on SATA. So it could be normal that I don’t have that option.

  3. Angel says:

    Great post, just a comment, in the 'Say What' section is DMA and not DMO.

  4. Thomas_mintywhite says:

    okay okay I get it.
    I wrote DMO instead of DMA
    I have corrected it

  5. Rich says:

    :) We have some sharp eyes around here :)

  6. Captain says:

    This often does not work I found the easiest way is download software “copy to DVD” (you can use the trial version) insert a DVD to copy, a panel will appear asking you if you want it to reset to DMA and hey presto it’s done. A point to note is that this usually happens if the DVD your copying has a flaw crack etc and Windows will reset to PIO Best of luck. Captain

    1. Anonymous says:

      thank you for your tip.

  7. Valentino says:

    Hey i need help, i click on the  IDE ATA/ATAPI Controllers tap, the i right click in what i have as Intel(R) Desktop/Workstation/Server Express Chipset SATA AHCI Controller i select properties and there is no advanced tab, so i cannot move on from there.
    what am i doing wrong??
    Thank you for the help

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