Originally Posted by Dave_5217 
what happens if you just take the jumper out completely?
I don't think any sata drive I've bought has come with a jumper on it, I didn't think they'd need them
Samsung are unlike other manufacturers and actually have two jumper positions for enabling the drive to operate on SATA ONE motherboards. This wasn't really applicable to my situation since my board supports SATA II but I had to rule out the possibility.
To clarify, the HDD came without a jumper cap at all. Of course I tried the default (no jumper) position first of all. I mentioned it just to show I'd been thorough and tried to rule out as much as possible that I could think of.
So no the HDD doesn't show full capacity without the jumper cap in at all. I've already discarded the jumper cap and won't be trying it again (it was a last resort).