It is like this in every game after the last beta.
CPU: Intel Core i7-4770K Stock
RAM: CORSAIR Vengeance Pro 16GB (2 x 8GB) @ 1333MHZ
Graphics: ASUS Radeon R9 390 STRIX-R9390-DC3OC...
It's more easy for me to explain my self with a picture since I'm not that good at English.
as you can see the gpu mem in game is different from that of the GPU tweak.
Thank you so much for making this software, a life saver, for my amd gpu.