Possible problem with my R9 290x Sapphire Vapour-X 8GB GPU

[ChrisPye999]

So I noticed this since I recently upgraded my PC but my 8GB card only seems to be registering 4GB of Memory instead of the 8GB that it actually has. Can anyone think of a reason for this to happen? I am using Windows 7 Professional 64bit and all of my drivers are updated to the latest version but under the DXDiag test that I ran it only shows 3817 MB of total memory. My computer specs are listed below in case it helps.

Windows 7 Profesional
Intel 5930k Haswell-E CPU
16GB G.Skill Ripjaws 4 RAM
ASUS X-99 Deluxe Motherboard
ATI Radeon R9 290x Sapphire Vapour-X 8GB GPU
Samsung 850 EVO 500GB SSD
Western Digital Black 2TB HDD
Corsair RM1000 Platinum PSU
NZXT Kraken X61 AIO CPU Cooler

I would greatly appreciate any ideas/solutions you have as to why this is happening.

Thanks.

[EDIT] - I'll also point out that I have searched through several pages on google and can't seem to find anyone else that has this problem.

 

[eyetrip]

Download gpuz and see what that lists for memory.

 

[ChrisPye999]

Download gpuz and see what that lists for memory.

Hmm OK so GPUZ is listing my GPU as having 8192MB of Memory which is good but what's going wrong for DXDiag to only show half that? Several games that I have played recently have only shown the 3817 MB number as well under the graphics settings.

 

[africanos23]

Hmm OK so GPUZ is listing my GPU as having 8192MB of Memory which is good but what's going wrong for DXDiag to only show half that? Several games that I have played recently have only shown the 3817 MB number as well under the graphics settings.

Download MSI afterburner and set graphics memory to show on screen.

Open up a game that has supersampling (VSR or whatever AMD's name is) set the highest resolution and preset possible aswell as 2x or 4x supersampling.

You should see the amount of VRAM being used. With those settings your are going to be over 4GB.