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I'm looking to put an expansion EIDE controller in my dad's desktop so it can handle a new 500 GB drive (evidently the motherboard EIDE controller has the 137 GB limit). He got a 500 GB USB hard drive for it, too, and I was wondering if that would work with the computer (with the new controller card in). Maybe I'm thinking about it wrong, I don't know, but it doesn't hurt to ask. Also, if it would work, would it be because of the new controller card, or not?

Update: important info: I have not updated the BIOS. I'm not sure that a newer version is available. There is no OS on the machine at the moment - only 500GB HDD. I have a XP disc with SP 2. The computer is at a shop right now, and the tech said the motherboard won't support over 128 GB hard drives. I'm thinking this can be overcome with an expansion card PATA/EIDE controller, but I'm still wondering if an external 500 GB is going to work, and if I would need the new controller card for it to work.

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Anybody have an answer for the question in case the BIOS can't be updated? – Nathaniel Oct 26 '09 at 0:06
up vote 4 down vote accepted

Are USB hard drive sizes limited by motherboard controller? Which controller do you mean?

If you're talking about the motherboard's hard drive controller (IDE/SATA), no.

If you're talking about the motherboard's USB controller, yes no.

USB's USB Mass Storage protocol is what governs USB storage. The protocol uses ATAPI (ATA Packet Interface) commands to access the drive. The ATAPI support is provided by a USB-to-ATAPI bridge chip in the external drive.

The USB-to-ATAPI bridge chip, and your OS, both need to support 48-bit addressing to get large-drive (>137GB) support. That's Win2000 SP3+, WinXP SP2+, and any versions of Vista and Win7.

The USB-to-ATAPI bridge chip is what might not support a large drive. If that chip uses the old 28-bit addressing (for the IDE backend), you'll hit the 137GB size limit. This is only a concern if you're buying an old USB enclosure and putting a new large drive inside it -- any prebuilt external drive will use a bridge chip appropriate to the size of the drive.

BIOS support for USB Mass Storage is only necessary for booting from a USB drive. I can't find any details, but even if your BIOS only supported 28-bit addressing, you could probably still boot from a partition in the first 137GB of the drive; once the OS is loaded, the BIOS limitations are irrelevant.

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+1 for actually reading and answering the question. – CarlF Oct 26 '09 at 2:12
Ditto.--------- – Nathaniel Oct 27 '09 at 3:19

Usually you can update the BIOS to support larger drives if the board is really that old. Also it can be a limitation of Windows if you have Win 2000 pre SP4 or XP pre SP1. An add-in controller shouldn't be needed.

Edit to clarify:

There are two possible causes for this.

1) Your BIOS is too old to support 48bit addressing, which will leave you with a max size of 128GB able to be recognized by your BIOS. The solution to this is to update your BIOS from the manufacturer's website. Many have bootable utilities if there is no OS on the machine yet.

2) Your OS doesn't support 48bit addressing. To fix this you can install with an XP CD with SP1 or higher integrated into it, or a Win 2K CD with SP4 integrated. If you don't have these CDs there are four real options.

-Borrow one from a friend (still use your product key to remain legal)

-Create the large partition in another computer that has SP1 or higher installed and then return the HDD to the computer it belongs in and begin the install.

-Use a bootable partition utility like gParted to create the partition before the install.

-Follow the registry trickery here;en-us;303013 though this is a pain and the least desirable solution.

I know you said it is a limitation on the motherboard, but you need to make sure it is also not a limitation with the install media that you're using.

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The computer is ~2004. Also, it doesn't have any OS on it at the moment, so I'm wondering about how to update the BIOS. Suggestions as to what to do? Also, it's in at a shop right now, so if a tech would have anything helpful... – Nathaniel Oct 25 '09 at 23:49
A tech should be able to download the dos-based flash utility and upgrade the BIOS from a bootable FreeDOS cd or the like. If your physical media is XP with no service pack on it, you cannot create a partition larger than 128GB. To get around this you can get a new XP CD, or you can create a partition in a machine with SP1 or later and then install it in the computer. – MDMarra Oct 25 '09 at 23:57
Ah, thanks. I'll look and see if there are recent BIOSs for the model. – Nathaniel Oct 26 '09 at 0:01
Sorry, I should have said earlier that the XP disc for it has SP 2 slipstreamed. – Nathaniel Oct 26 '09 at 0:11
Gotcha, then I'd say a BIOS update is in order. I'd update your original question so other can see that without having to read the comments to my answer. – MDMarra Oct 26 '09 at 0:17

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