I just bought a new HDD of 3TB (not yet shipped). I didn't know that size is normally not supported to use it to boot OS. I learned I need a computer that supports UEFI so that I can install windows on that disk.

My first problem is: I have a laptop (Asus N61VN) and I have no idea if it supports UEFI. I used google (ofc) but no results showing wether it supports UEFI or not. How can I check if my motherboard supports UEFI?

Second, I don't have to use whole 3TB as one partition. Let say I partitioned my disk like 500GB+1TB+1.5TB. Can I install windows on that 500GB HDD and boot it? Does this partitioning require any different procedure than the "classical" partitioning I know?

Thanks a lot.

  • 1
    The Asus N61VN uses a BIOS firmware not UEFI firmware by the way – Ramhound Aug 2 '14 at 12:39
  • btw... what 3 TB drive did you find that would fit in a laptop? The largest capacity I find at Newegg is 2 TB and even that is 15 mm high - the standard 2.5 inch laptop drives are only 9 or 9.5 mm. – Jamie Hanrahan Aug 11 '14 at 1:46

Assuming you don't have an EFI firmware, I see a number of options:

  • Ditch the computer and buy another one.
  • Return your new disk (or use it somewhere else) and buy a 2TB model instead.
  • If the computer supports two disks, use a sub-2TB disk for the Windows boot disk and use the 3TB disk (with GPT) for data. Note that you can probably get a kit to put a disk in your DVD slot. Since DVDs are much less important today than they used to be, this might be a good excuse to get yourself a small SSD for use as a boot disk. (Note that a BIOS-booted Windows 7 can use GPT as a data disk; the BIOS/MBR and EFI/GPT linkage applies only to the boot disk.)
  • Resign yourself to using only 2TiB (about 2.2TB) of your new disk.

The above options are the ones that are the easiest and the least likely to cause problems. There are, though, at least two other options:

  • You can, as you suggested, partition the disk in chunks. Because of the way MBR works, it's technically valid to create a partition that begins just below sector 2^32 (2TiB) and that has a size of up to 2TiB. I don't know offhand if the Windows partitioning tool will create such a partition, but it can be done. IIRC, I used Linux's fdisk to do it. In my tests, Windows 7 was able to handle such a disk; however, my testing was extremely limited. There might be some serious "gotcha" that will end up chewing up your data. This is particularly likely if you've got 32-bit drivers that aren't explicitly coded to handle 64-bit disk addresses.
  • You can try using DUET or Clover. These are both, essentially, software EFIs. They run as boot loaders on a BIOS-based computer, thus enabling Windows to boot from a 3TB (or larger) disk. One caveat is that they work best on Intel CPUs -- but I see your ASUS N61VN has an Intel CPU, so that's probably not a big deal for you. Clover is the prettier system, but it's a Hackintosh boot loader that will be easiest to set up if you've got a Mac. (Once set up, you can use it just for Windows.) DUET is less pretty by itself, but if you're single-booting you probably don't need the pretty boot menu; and if you did you could add rEFInd.

If you've got ~US$100 to spare and don't need a DVD drive, I'd probably go with converting your DVD slot to hold an SSD. I've seen conversion kits online for ~$25, and SSDs can be had for well under $75. The DUET/Clover approach can be quite effective, but it requires more in the way of technical skill, or at least the ability to follow technical directions.


This page provides instructions for a hack to enable installing Windows to a GPT disk to boot under BIOS mode. I haven't attempted to do this, but for somebody who still need to do this, it might be worth trying.

  • I've heard somebody said that you can also create a virtual MBR harddisk in the GPT harddrive when installing windows then install windows to that virtual drive, it'll boot normally but I haven't checked it yet – phuclv Aug 2 '14 at 17:39
  • There is a type code for a virtual MBR disk on GPT; however, I've never heard of Windows 7 supporting installing to a GPT disk on a BIOS-based computer using this type code. If it works, then that would indeed be another possibility. Note that this would require creating TWO virtual MBR partitions on the GPT disk, since each one would be limited to no more than 2TiB. – Rod Smith Aug 2 '14 at 17:47
  • you only need to create a small partition enough for installing windows 7 because windows 7 can recognize the remaining GPT partitions for data – phuclv Aug 2 '14 at 17:54
  • Yeah, I guess you're right. If you've got a pointer to a site describing how to do it that way, I'd be interested in seeing it. – Rod Smith Aug 2 '14 at 18:01
  • I saw it in a Vietnamese forum but unfortunately the guy who claimed that just said that he was using windows that way and didn't provide any link. Here is another different way but also use windows VHD drive – phuclv Aug 2 '14 at 18:14

You can install Windows on it with your non-UEFI computer, but it will only let you use the first 2 TiB (slightly more than a "2 TB" disk).

Windows will not let you create partitions that extend into, or start in, the region beyond the 2 TiB point. So in your example you would not be able to create your third partition (1.5 TB).

( The reason is that MBR partitioning uses 32-bit integers for partition start and size. The numbers are expressed in LBAs (logical block addresses). A block is 512 bytes. With a 32-bit integer you can have 4 x 1024 cubed different LBAs. At 512 bytes per, that's 2 TiB. )

Depending on who made your drive, the drive manufacturer may have a utility that will help, such as Seagate DiskWizard. Whether or not this will work for a boot drive, I don't know.

  • As a dude who had 500GB for years, 2TB is enough until I upgrade my computer. I have only used BIOS and MBR partitioning until now. Do I need to apply any different procedure to use that first 2TB to boot Windows? – Hasan Aug 2 '14 at 11:58
  • 2
    @Zagooda - No; Windows will simply be unable to create a partition larger then 2TB during the installation process. Additionally the ~1TB will be unallocated, it will be basically invisible to Windows. If you want 3 TB system disk that requires computer which uses the UEFI firmware at least in the case of Windows installations. – Ramhound Aug 2 '14 at 12:37
  • btw, you can fully use that drive as a second drive for data. The legacy BIOS firmware (i.e. non-UEFI firmware) can only boot from an MBR-partitioned disk, but the firmware is not in the loop for any other disk access. So if you can put two disks in your machine, you can keep your OS on your existing drive and connect the 3 GB drive for bulk data. Right-click on it in Disk Manager and select "Convert to GPT", then you will be able to make partitions that use all 3 GB. – Jamie Hanrahan Aug 2 '14 at 18:09
  • @JamieHanrahan he can't use GPT because he has a machine that only support MBR. He has a single disk not two hence my replnse – Ramhound Aug 4 '14 at 19:41
  • @Ramhound well, I did say "if you can put two disks in your machine" :) Presumably he does have two drives, the 3 TB he just ordered and the one the laptop came with? There are a couple of different ways to use the 3 TB drive as a second drive. There's the obvious (a USB hard drive enclosure), but there are also adapters that let you install a second HD where the optical goes. – Jamie Hanrahan Aug 4 '14 at 20:13

The size of the partitions isn't the problem, its the partitioning system itself. You might have heard of Master Boot Records (MBR) right? Well they are depricated now, 3TB disks need to use GPT (GUID Partition Table) - thats why you need UEFI.

More details here:


Onward to the next question: does my laptop have UEFI?

Easiest ways to find out:

  1. Ask your vendor 2 Can you move your mouse in your (UEFI)"BIOS"?

btw: I noticed the tag "Windows 7" on your question. You need to have the 64-bit Version to use 3TB disks.

  • I used windows 8 in my computer once. And it worked flawlessly. Tell me I can boot from that 3TB disk and I'll buy you ice cream. – Hasan Aug 2 '14 at 11:45
  • I can't move my mouse on my BIOS. It's plain old ugly BIOS screen – Hasan Aug 2 '14 at 11:46
  • 1
    Well that thing looks rather new, comes with an Intel CPU and the ice cream sounds tempting ... Yes, if you use Windows 7 or 8 64 bit you will be able to boot from that disk AND use all 3TB of it. Btw: where did you find a 3TB 2.5" disk? That sounds rather exotic. – Manfred Radlwimmer Aug 2 '14 at 11:50
  • Windows 8 does not require UEFI. I have several machines here running Windows 8 with PC legacy BIOS. – Jamie Hanrahan Aug 2 '14 at 11:52
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    @Mario - Secure Boot support become a requirement for Windows 8 OEM machines when it was released ( it also must be possible to disable it ). If there is a Windows 8 OEM machine not out there, then its likely not actually authorized – Ramhound Aug 4 '14 at 21:52

Regarding the question "How can I check if my motherboard supports UEFI?":

It's not the motherboard that supports UEFI; it's the BIOS chip. Electronics-wise, nothing is different between legacy BIOS and EFI BIOS. You can re-flash your BIOS with a EFI version. That's not to say that if you're unlucky and you get a corrupted image, you won't end up with a bricked computer. I know I wouldn't have tried to do so unless I had a robot specifically designed to solder those little chips in/out and a chip flasher, which I don't.

P. S. You said that yours is an Asus computer. If you need BIOS images, I would recommend going not to asus.com, but to asus.de: the German version has newer driver versions.

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