1070 Showing only 4GB

[Shojar]

I bought the Gigabyte G1 1070, and in SPECCY and Heaven Benchmark it's only showing it to have 4GB. Whereas the box and product say it has 8GB. Is there something I've done wrong?

I installed the latest drivers and Gigabyte's software for it.

 

[Sergeant_Sneaky]

What does GPU-Z show?