Yes, they will overheat really easily if you keep then in the enclosure purchased with the drive.
I initially suggested external ones as they're slightly cheaper and the casing merely pops away from the drive. Then, put them into a NAS enclosure or an old server and that will keep them cool enough to function.
Thanks for the advice mate. Perhaps, mining with HDD would be more accessible than with ASICs. HDDs can be found even much cheaper than ASIC hardware, in my opinion, and more accessible and easier to find. For cooling, I had this crazy idea of using USB powered fans connected to a USB Hub to cool off the HDDs.
