Solved: Need to enable DMA mode on HD using the (((shudder))) Registry Editor!!!

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tiger_eddie

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I have already enabled the "use DMA if available" in the Device Manager but XP seems determined to keep me in PIO mode. Googling suggests making changes to the registry to solve this but are very unclear (to me) about how to go about this.

MY SYSTEM IS:

Dell Dimension 4400 running XP Pro sp2
Pentium 4 1.59 Ghz
1 GB RAM
Primary Disk: 80 GB Hitachi Deskstar 7200 rpm Parallel ATA
Secondary Disk: 80 GB Maxtor 6L080L4 7200 rpm Ultra ATA/133

BTW, I have never edited the registry and am completely intimidated by the thought of it.
 

crjdriver

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Some dells have the secondary ide set to pio mode in the bios. Check that first.
Before you edit the registry, make a backup of at least the keys you are working on. Preferably make a complete image of your system.

Next if it is a secondary hd or cd / dvd drive giving you problems remove the devices from device manager along with the ide controller in question.

If that does not work, here is how you edit the registry.

Run REGEDIT. Go to the following key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E96A-E325-11CE-BFC1-08002BE10318}

It has subkeys like 0000, 0001, 0002, etc. Normally 0001 is the primary IDE channel, 0002 the secondary, but other numbers can occur under certain circumstances. You have to go through these subkeys and check the DriverDesc value until you find the proper IDE channel.

Delete MasterIdDataChecksum or SlaveIdDataChecksum, depending on whether the device in question is attached as master or slave, but it can't actually hurt to delete both. Reboot. The drive DMA capabilities will be redetected.

Note that many CD and DVD drives only use UDMA-2, because their data rate is much lower than that of a hard disk. This is normal and no reason to worry.
 
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tiger_eddie said:
BTW, I have never edited the registry and am completely intimidated by the thought of it.
If you are considering editing the registry I highly suggest that you backup the registry prior to making ANY changes.

If you are running XP Home edition the Microsoft backup utility is not installed when the operating system is installed. To install the backup utility in XP Home read the instructions at;

http://support.microsoft.com/kb/302894/

It is a very simple procedure to install the utility.

To use the backup utility after you have installed it read the instructions at;

http://support.microsoft.com/kb/309340/

At this link be sure and watch the short video presentation.
 

JohnWill

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Of course, creating a system restore point will also accomplish a backup of the registry, and it pretty easy to do. :) DMA Reverts to PIO will describe the process of fixing this issue. They also supply a .VBS script that will do the correct settings, so you don't have to manually edit the registry.
 

crjdriver

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I keep forgetting about the restore points. :) :) I use win2k all the time at home and most of the time at work [where they do not let us do anything with the machines anyway]
 

JohnWill

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I forget restore points a lot too, but I'm getting used to using them, and they have saved me from firing up True Image and restoring my last image several times. :D
 

MysticEyes

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I'll throw in my 2 cents.

In Device Manager if you try to enable DMA and if the drop-down box already shows 'DMA if Available' but the current transfer mode is PIO, then try toggling the settings.

That is, change the selection from 'DMA if available' to PIO only (so now they match), and click OK. Reboot come back and see if you can enable DMA now.

Works sometimes.
 

JohnWill

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If you read the text on the page I posted, you'll find that XP sets a flag in the registry that you need to clear to get DMA working again.
 

tiger_eddie

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The settings in the BIOS were correct so I created a restore point and ran the .vbs that John suggested and rebooted-but it still didn't take-so I had to manually delete the "MasterDeviceTimingModeAllowed" and SlaveDeviceTimingModeAllowed" from the registry. After a second reboot, it still wasn't working!:mad:

(There was a recent United Airlines commercial where there is a woman giving a presentation to a boardroom full of obviously-displeased animal-headed people and one of them with a wolf-head is biting the conference table. That is a good illustration of how I was feeling.)

I decided not to bite my desk (it has a faux-granite top) and instead updated the IDE and ATA controller drivers. I rebooted again and now it seems to be working-I tried to check in Device Manager and the Advanced tab for checking the DMA settings is no longer there (should I be concerned about this?) but the computer is running much faster now so I know it worked.

:) Thank you everyone!!!
 

JohnWill

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It's curious the advanced settings disappeared, hope you don't need them. :D
 

MysticEyes

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-I tried to check in Device Manager and the Advanced tab for checking the DMA settings is no longer there (should I be concerned about this?)
I've noticed this also when installing Intel's IDE accelerator drivers, no more DMA tab, if this is what you installed.
 

JohnWill

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That makes sense, I didn't connect the "updated drivers" with the Intel Application Accelerator.
 
Joined
Mar 27, 2007
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As MysticEyes said the DMA mode disappears when Intel acclerate drivers are installed. Since I had some problems with the hd perfomance I'd like to uninstall this driver but don't know how. Any suggestion how to do?
 
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