Gpu not using full vram

[Redbeardthebearslayer]

I just build my first pc and I have been running some benchmark tests to see how everything is running. I have been a little let down by my firestorm and heaven score. I have done some checking with Cpu-z and it is saying that my Gpu only has 4gb of memory which should not be correct. If I go to screen resolution, click advanced settings, it shows my gpu has 8gb of vram.

How can I check to see how much vram my gpu is using?
If it is capped at something less than 8gb how do i raise it?

Cpu Intel i7 5930K 3.5 6-core
Motherboard EVGA Classified x99
Memory Corsair Vengeance LPX 16gb (4x4)
SSD samsung m.2 128gb
HDD western digital wd green 2TB
Video card Asus radeon R9 390 8gb
Power supply corsair 1000w 80+ platinum

 

[bloodxakep]

You can chech with MSI Afterburner app, also games like GTA 5 can only use ~5GB of VRAM.Now it's useless to have 8GB VRAM(IMO)