750GB inaccessible space on HD

[Aweigel1]

I just built my pc yesterday and I'm encountering little problems here and there. I've got one that I can't figure out here. My hard drive has about 750 inaccessible GBs. It's a 3TB drive and my storage says 2 TB available. I'm not sure how to work around this, as I cannot select new simple volume. Here's a pic of my problem http://imgur.com/a/xVkP1

 

[popatim]

Looks like you partitioned it as MBR instead of GPT and MBR has a 2TB max drive size limit.