Windows – 4TB drive only showing as 1.6TB

biosgpthard drivepartitioningwindows 7

So as the title says I have a 4TB drive I want to add as a secondary drive in my PC. I will not be booting off this drive. It is new, and not formatted in any way.

I'm running Windows 7 Pro 64bit SP1 and in Disk Management the disk only shows up as 1.6TB. I see no option to convert to GPT disk, which I believe is what I need to do.

I was hoping you guys could give me an idea where the limitation is coming from (i.e motherboard, OS, BIOS).

PC: HP Pavilion p6210uk Desktop
Motherboard: PEGATRON Narra6 Nvidia MCP61
BIOS: American Megatrends Inc. 5.15 (06/11/2009)
HDD: WD Green 4TB Desktop 3.5 inch Internal SATA Hard Drive

Unfortunately the HP website doesn't seem to list an update for this BIOS so I'm kinda stumped just now. My next troubleshooting route is going to be upgrade to Windows 10 which is a lot of effort just to rule out the OS.

Thanks guys

Best Answer

Your problem is neither your Windows version nor your BIOS. It's almost certain you've got a driver somewhere in the mix with a 32-bit limitation on its sector values. This sort of problem usually manifests as disks showing up as smaller than they actually are. The problem is most common on 32-bit versions of Windows, but I've heard of it on 64-bit versions, too.

If you want absolute verification that this hypothesis is correct, boot a Linux emergency disk and use it to examine the disk in the computer that's giving you problems. If Linux enables you to set up the whole disk, then I'm right and it's a Windows driver problem. If Linux sees the disk as being 1.6TB, then there's something else going on.

If I'm right, you'll need to search for a way to swap out your bad driver with a good one. Sometimes switching from "IDE mode" to "AHCI mode" in the firmware will force such a switch, but this will also sometimes cause the computer to stop booting (at least for Windows, which is very finicky about such things). There are sites that describe how to do such a switch and recover from it, but I don't have any pointers offhand. A Web search should turn them up, though.

Another option is to look for updated disk controller drivers. Check your motherboard manufacturer's Web site and/or the site for whoever created the chipset that's driving the disk. (Note that it's not the disk itself that's the problem, so WD's site is unlikely to be helpful. It sounds like you've got an Nvidia chipset, so that's one place to start -- but it could be the problem is on a secondary disk controller chipset.)

Yet another possibility is to move the disk from one port on the motherboard to another one. Almost all computers have multiple disk ports, and these sometimes connect to two different disk controllers. This is particularly common if the motherboard has more than four SATA connectors. The idea here is that the driver for Disk Controller A is defective, but the driver for Disk Controller B may be OK, so switching from one connector to another may fix the problem. Check your documentation for clues if this might be the case, or just try moving the cable around and hope for the best.