I feel I should preface this with a little background. I bought a new rig, including a PNY GTX 680 4GB last May, and around 2 months ago it crapped out on me. Any game I ran would instantly throw my GPU usage to 100% and throw my fans into overdrive.
I raised the issue with my supplier, as per my warranty in the first year, and found that I had to send it to the supplier for repair or replacement, which I did.
The supplier (an Amazon seller with high rep and thousands of sales), mailed me back and said they'd found no problems with the card, but would replace it as agreed.
The result was my new GTX 770 arriving. It came wrapped in the bubble wrap I'd mailed the 680 in, and the same box I'd bought from the post office. Regardless, I plugged it in and have been using it since, until I ran Watch_Dogs and noticed something strange.
I was getting dips in FPS where realistically I shouldn't have been, and so I ran MSI Afterburner in the background, and my Memory usage is capping at 2GB. I ran DXDIAG, and it reports a 4GB GPU. However I ran Nvidia Inspector, and it reports 2GB.
I downloaded GPUZ as an impartial monitor, and it shows me 2GB of GPU RAM.
I'm really at a loss what to do, as I feel I may have been cheated by the supplier. Is there any way to definitively check the VRAM my card is capable of outside of using the programs I mentioned?
a) Start-> View-> System Information
b) go into the "GPU" section
c) at the bottom, left you'll see the DEDICATED GPU MEMORY, and the "limit" is how much you physically have available.
I doubt there's really a problem. The programs reporting 2GB may not be correctly identifying the amount of memory but I'm sure it's there and usable.
As for the dips in Watch Dogs, well there are currently lots of issues with that game. I strongly suggest NOT running Ultra either. Try going with HIGH or whatever keeps your frame rate above 40FPS. Two best choices are:
a) 40FPS with VSYNC OFF, or
b) 60FPS with Adaptive VSYNC forced on (settings tweaked so rare dips below 60FPS). If 50FPS is supported choose that.
Both methods have Pros and Cons. If Screen Tearing isn't a big issue for you then choose the first method.