HDD from previous pc detected but no drive letter and inaccessible on new pc

[donnywankan]

My pc's video was crapping out, so I bought a new pc. I backed everything up to a 5tb hdd I had on the old pc, which was working fine, and I put it into an external enclosure to bring all my files to the new pc. When I plug it in, via usb, I get the notification sound, but it doesn't show up as a drive.
I can see it in the Disk Management utility as online and healthy, but I can't do anything with it. I tried through a command prompt to see if I could change the settings through diskpart, but it doesn't see it there. I also tried the Aomei software, but that didn't see it either.
In Disk Management, it shows as "GPT Protective Partition." I suppose something in the partitioning has locked access except for the install of windows it was attached to in the previous machine.
Is there a way to bypass the lock, or, alternatively, is there something I can go back into the previous machine and do to the drive so that it won't be locked when I bring it to this one? I don't want to go through the trouble of reassembling that machine, but I had backed up all my important files to that drive.

 

[clutchc]

Does Windows disk management allow you to assign it a drive letter and initialize it?

 

[R0GG]

_GPT Protective Partition.mp4 >> very quick and easy to follow instructions video: https://www.youtube.com/watch?v=QbRGFiigB5c
_ Troubleshooting GPT Protective Partition Issues: a step by step tutorial >> http://knowledge.seagate.com/articles/en_US/FAQ/207837en

 

[donnywankan]

clutchc, no it doesn't allow me to do anything. The options are all grey.
ROGG, I'll take a look at that and post an update. Thanks.

 

[punkncat]

http://www.tech-faq.com/gpt-protective-partition.html

 

[R0GG]

Sounds good mate, I'll wait for your feed back.

 

[donnywankan]

Update: Tried all the suggestions. Still running into the same problem. The computer sees the drive there, but blocked out of options for making it readable or writable. The closest I've got is getting to the option of changing from GPT to MBR, but since the drive is almost 5 terabytes, it won't handle MBR without completely destroying info and starting over. It starts the process of changing the setting, then it stops and gives an error about needing to break the drive into more than 4 partitions. I'm trying to avoid wiping it out.

 

[mdd1963]

Does the external chassis you placed the drive in get power from USB?

Most drives of that size would need an AC adapter, and would likely be incapable of drawing enough power to function just from a USB port of any type...

 

[R0GG]

What operating system are you running?
Try connect same drive internally directly to motherboard through SATA interface, reported to have solved similar issue.

 

[punkncat]

From what I understand of the link I posted. Your HD was "created" in an enterprise environment and what it's doing now is a protection to KEEP you from changing it. I would imagine that you need the program/device that created that protection to undo it.

 

[donnywankan]

mdd1963, yes, the enclosure has ac power.
ROGG, I had thought about that, but I'm not sure if I have room inside the new pc for another hdd, and I really don't want to take that one apart. It may be where I end up going with it, though. I've built my own in the past, and I was trying to avoid putting my hands on the internals on this one because I always seem to mux something up in the process. I'm one of those guys with just enough computer knowledge to cause these kinds of problems for myself.
Right now, it's looking like the alternative to the last suggestion is to slowly back up all those files via thumb drives or the cloud.

 

[donnywankan]

punkncat, I have actually tried to change the settings on the old machine, but although it will let me read and write, it won't let me do anything else, other than wiping it and repartitioning. I'll explore a little more, but it's looking more and more like I'm stuck with a hard way out.