Sure, Gaylon.,

What you are seeing, is a 3x2 image that is the format of your camera being (no cropping) placed in an 8 x 10 frame.
So the print fills out the 10 inch side of the frame, and stops!
The 8 inch side of the frame can only go to 6.67 inches because that represents a 3:2 image ratio.
If you wanted a full 8 x 10 image, the 10 inch side would have to bleed off the edges of the 10 inch sides until the 8 inch side filled out.

So you either print on 8 x 10 and accept the white margins, or select a print size that matches the 3:2 image ratio from the camera.
That would be be a 4 x 6 (3:2 doubled), or any multiple of that.

You have another option which may or may not help.
Set the print size to 8 x 10 with auto crop on.
Then go into the Full Page Editor screen, selecting the Crop Tab.

Now use the mouse pointer in the small upper right corner box and move the image around in that box. You might be able to locate the subject material within the 8 x 10 frame. Then you can print your 8 x 10 full.

Fred

Full frame just means that there is no built in cropping. The sensor can handle the full frame.
The format of the camera still is 3:2.
There are some new model cameras that allow you to select 3:2 or 4:3, 16:9, and 1:1 formats. 

Fred

I did some googling, and all I can find is resolution of 5616 x 3744 which computes to 3:2.
That's pretty standard for most SLRs so I wouldn't get concerned in any way.

Fred