@Olliver17 As I don't know what workarounds you already tried, I will provide you several troubleshooting steps. If you could give us more details about your system (like DXDIAG) it would help us to investigate your issue.
Okay let's check:
At first, please check your latest video-card driver and check what version of the origin client is installed on your computer. Install the newest driver for your video card. Go to your custom settings of your video-card software. Disable all extra options for enhanced graphics and set the preferences for AA and anisotropic to “use application settings”.
Set the DS3 graphic options to “low quality” or reduce AA and anisotropic filtering to a minimum.
Launch the game, if the issue is solved, you can try to set the graphic options higher.
Try to run the game in "windowed mode" and test it for a while.
Please note: Even if your system specs should be totally fine for running DS3 in high resolution, there are sometimes graphic setups which can cause issues on several systems.
Right click in Origin under "my games" on the Dead Space 3 icon and choose "Repair".
If you running on a Windows 7 64bit system, you can try to run the Client under the Windows 7 compatibility mode. The Windows 7 compatibility mode is running as x86, and helped in a few cases to solve this issue.
Please keep us updated.
Basti
