usb hard drive shows completely different partitions when directly con

Persumably yes. So I am going ahead with that presumption that you bought a second hand used 3TB Seagate external drive and you took the HDD out prying the case open.

Since you took the two screenshots one with the 3TB HDD inside the external enclosure and one with the bare 3TB HDD connected internally, I am also presuming that the external case is still serviceable.

Now here is the answer.

Your 3TB HDD inside the enclosure came as an Advance Formatted MBR drive. There is a specific drive translation circuitry in the external enclosure's interface electronics to write and read the data into 4096 byte sector size. When you take the drive out and use the bare 3TB HDD as an internal drive this drive translation circuit that does the 512 byte to 4096 sector size and vice versa is absent. That is why you see a different jumbled up partition structure.

If you want to use the 3TB HDD as an internal drive you should now format it as a GPT drive.

Try deleting the RAW and the two unallocated partitions with Windows Disk Management, initialise the drive as GPT and then format the drive.

If you have any problems report.

( Now I am asking this question just out of curiosity. The user must have had some reason for disposing off that external drive. When inside the external case, were you able to read any data on it? Though I had given you the reference Disk Management - Post a Screen Capture Image you don't seem to have read that and followed the guidelines indicated therein to present a full screen untruncated screenshot. In the second screenshot you posted showing the drive inside the enclosure, I am unable to see the Capacity, Free Space and %Free in the drive list above. It is obscured by the Action pane.The tutorial tells you how to hide the Console Tree and Action Pane so that all the information is seen on the screenshot.)

Given it is second hand I'd run the Seatools diagnostics on the drive. I'd start with the short tests then run at least one of the long tests (and they will take many hours for 3 TB).
You need to decide if you want to use it as an external (with its current enclosure) or an internal. It's one or the other. If you format it for internal drive use then you do it at your own risk.

OK, good that you have finally made up your mind to use it as an external drive with the 3TB HDD back into its heavenly abode. :)

As mjf suggested download, install and run SeaTools for Windows

SeaTools for Windows | Seagate ( Read the instructions on that download page)

Read the user Guide here http://www.seagate.com/staticfiles/s...dows.en-US.pdf ( Read,Read, Read....it. You learn things only by reading)

Run the Short Generic Test and then the Long Generic Test. After completion of both tests, go to Advanced Tests - "Full Erase (SATA)" and write zeros to all sectors to clean the drive.

After that initialise the drive as MBR and format it. ( Partition it if you want to.)

Note:If the Short Generic Test fails, you have to download Seatools for DOS, burn it to a CD boot from that CD and run the tests. Only the DOS version has the ability to repair. Read the User Guide for the DOS version..

If you have any problems, don't hesitate to ask for help.

In a nutshell,

1. If you want to use the 3TB HDD in its original external casing, clean wipe it and initialise it as an MBR drive and format.

2. If you want to use it as an internal drive inside the Desktop,clean wipe it, initialise it as a GPT drive and format it ( There is absolutely no risk in initialising it as a GPT drive.)

You cannot change the drive from here to there and there to here.

Note to others who read this thread: Now that Windows XP is no longer supported, the drive manufacturers have started abondoning Advance Formatting with MBR initialisation - which was necessary till now to make the larger than 2TB external drives compatible with Windows XP - and have started changing over to GPT initialised larger than 2TB external drives in phases.(model-wise.) Now it is a transition period. The new larger than 2TB external drive you buy may be GPT drive or Advanced formatted MBR drive. Check and note whether it is an MBR initialised drive or GPT initialised drive.