Video card discrepancy on new computer

[jdob22]

I just purchased this dekstop:

http://www.powerspec.com/systems/system_specs.phtml?selection=G180

The video card is listed as being a 1 GB AMD Radeon HD 6670.

However, if I run DxDiag and look under display, the Approx. Total Memory is listed as "705 mb'. Also, canirunit.com approximates my video memory as "706 mb".

Is this discrepancy normal?

 

[DominionSeraph]

It happens.

What does GPU-Z say?
It should only come in 512MB or 1024MB versions.