Can I take apart an External HDD and Place the Drive into my Computer?

[Silmarilos]

Hello internet.

So, I am interested in buying 3-4 new 4tb hard drives for a NAS/ RAID storage I am setting up in my home. I have the device decided on and now I need the storage. I am having trouble figuring something out and hope you all can help me.

I have purchased internal hard drives in the past and purchased an enclosure to make them external. This makes sense to me. I am unsure, however, if the new ones function the same way in reverse.

IE, If I buy this item:
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=7739051&CatId=4230
and take it apart, will I have a shiny new 4tb ready to place into my new NAS/ RAID storage unit?

If it WILL NOT work, why?

If it WILL work, why are the external expansion drives like the one listed above so much cheaper than buying an exposed internal 4tb hd like these 2?
1) http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=8526737&CatId=139
2) http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=9149262&CatId=4357

Thanks all for your help!

-Sil

 

[boosted1g]

Most new external HDD have firmware locked preventing them from being used outside of their casing.

Also an external is cheaper because the drive is cheaper, they wont handle the stress very well that raid arrays put on drives.

 

[HST_James6666]

You should not buy external HDD's to use inside your PC because they will be alot slower than alternative Internal HDD's, this is because they are bottleneck by USB 2.0 or 3.0 therefore never need to run past 100MB/s also 3tb HDD tend to be better value than 4tb, probably something to do with the amount of platters packed into one place. This is the best value HDD by the same company I found:
http://www.amazon.com/dp/B005T3GRLY/?tag=pcpapi-20
In theory it should have a higher RPM than the External Desktop HDD which are usually 5200 or 5400. It will cost you about $20-$30 more using the HDD's above than the External Desktop HDD, for 12TB of storage.

 

[fzabkar]

I've never heard of external drives being limited by firmware in any way other than via the USB-SATA bridge hardware. If you can separate the actual HDD from the bridge electronics, then it should function internally as a regular HDD. However, since some bridge firmware is configured with 4Kn sector sizes, the drive may need to be reformatted when swapped between internal and external applications.