Can i build a pc with a external hdd

Solution
Can you: yes
Should you: no.

Your external drive is slower then an internal drive from the get go, then USB 3.0 will be slower then sata, external drive is lower quality, and is a fall-off-your-desk away from drive failure.
Not to mention the instability you might get from doing this.
[strike]Yes.
When in the OS installation, select the main partition of your USB drive.
This setup you be efficient as you will be limited to USB 3.0 Speeds and won't make use of your motherboards 6-10 GBS SATA 3 speeds.
[/strike]
Never mind, Im probably wrong.
 
assuming you refer as usb external hdd.

so it depends on the os...

if windows, no - you will not be able to select the external usb hdd as a target for installation (or at least i'm not aware).

if linux, yes - there are certain distributions that allow making usb boot drive and then enable some persistence so that you can also write to the drive and save files, etc.

but overall, speed will not good enough for a nice experience. even if usb 3... i think will still suffer.
-s
 
Can you: yes
Should you: no.

Your external drive is slower then an internal drive from the get go, then USB 3.0 will be slower then sata, external drive is lower quality, and is a fall-off-your-desk away from drive failure.
Not to mention the instability you might get from doing this.
 
Solution