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What are the consequences of Disabling a Drive in the BIOS


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BIOS (American Megatrends version 2202.)


Under BIOS selecting BOOT menu and choosing the sub-menu "Hard Disc Drives",

I always see my three internal Drives from OCZ, SamSung, and WDC,

UNLESS I have selected DISABLED against WDC in which case it is not shown.


I suspect that when WDC is disabled then it cannot be considered as something to boot from when all else fails.


Am I correct ?


Are there any other consequences - e.g. preventing normal power saving "spin down" when no data has been transferred for a while ?

I have found that I can still read and write to the WDC whilst it is "DISABLED", though I have not tested whether speed is affected ?



Most times the WDC is Disc number 0 but sometimes it is Disc number 2.

This has no ill effect on partition letters etc.,

BUT some "Task Bar Notifications and Icons" give me false information because they are referencing Disc Numbers,

and I only knew the information was false when I launched Windows Disc Management and saw the Physical Drives had been shuffled.


I am planning on leaving WDC "DISABLED" for a month to see if this results in more consistent numbering.


N.B. Not only do I not wish to boot from WDC, but I cannot because my BIOS cannot boot from a GPT drive.

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Alan, it has been my experience that the following things occur when you disable a drive within the BIOS.


- The BIOS doesn't show the drive on bootup

- The drive is eliminated as a bootable drive

- Booting will be quicker, because there are fewer drives to engage

- Task manager within Windows fails to show disabled drive


There may be variances among different BIOS makers, but the above stated is usually the case.


Sometimes, you may need to disable "Autodetect" for the drive you are wishing to disable. If you are disabling a drive, I recommend disconnecting the power & data connectors as well. This prevents extra wear on your drive, because while it may not be in use, it will still spin up & Windows will more than likely not power it down. If it powers down, likely a setting in the BIOS or power saving built into the drive (Green drive).


I am uncertain if you are referencing older PATA (IDE wideband) or SATA (Modern narrow band) connectors. But I know SATA has only 1 drive per ribbon. PATA can have 2, depending on a number of factors. Ribbon condition, whether it is enabled or disabled in the BIOS, Master/Slave/Cable Select properly selected. On PATA drives, you can have only one master, & one slave. If you have master/master, the drives will not appear in Windows itself. Same if you have slave/slave. You may have Master/Slave, Master/Cable Select, Slave/Cable Select, or Cable Select/Cable Select.


I like SATA, because they are up to 30% faster, & don't have to share a data ribbon. There are no configurations to mess with, & the cables are less likely to mess up from the pins clamp separating from the data ribbon wires.

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My drives are connected by SATA.


How would I disable "AutoDetect" ?


Once Windows is running I have seen the drive as being available and useable.

I will not disconnect cables because this is the drive that holds my Partition Image backup files and also my Internet Download folder.


You have confirmed my expectation that Disabling the drive prevents it from booting,

and if the BIOS is quicker and has less interaction with this drive perhaps my Disc Numbering might be more consistent.


I think I will just go ahead and leave this disabled - assuming read and write speed is not adversely affected.



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Normally, you can disable a drive by disabling the controller listed for it in the BIOS.


Different BIOS makers use different methods to disable. For some, you hit space key to expand/collapse/enable/disable devices or options.

For others, you use arrow keys or U for up & D for down + enter to enable/disable.


Usually, they will list near the bottom of the screen what keys are needed to change pages/options, & some options may be listed on a different page.

On older BIOS models, page up & page down may be used to switch pages as well as various other ways.


* You may have to select none to disable automatic, from a menu listing manual/automatic/none. The options change from BIOS to BIOS.

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