A crash at that point in loading is likely either:
- running out of VRAM
- encountering bad VRAM
- hardware fault
- driver fault (game asking driver to do something it doesnt like)
A 6800 should have 16GB of VRAM and I have run the game on it. However, KSA does not currently swap assets out of VRAM so other things running will utilize some VRAM. Running out of VRAM during game load will almost certainly result in a crash, running out of VRAM *after* loading will result in slide-show FPS.
Because KSA loads everything it needs onto VRAM this can put your GPU through its paces in ways most other games will not. Many games might only utilize 1-2GB of VRAM at once. This means you might not be touching the rest of your card. There are plenty of games that will use a lot of your VRAM though, so if you have no problem with very modern games that are confirmed to be using all of your VRAM, it won't be a memory hardware fault. You can use AMD's tools to check the GPU for memory faults.
Thirdly if your GPU overheats or has voltage issues, this can result in crashes. Although typically this would involve BSOD or hard restart of the OS, as the GPU not getting enough voltage or overheating can usually result in that outcome. Again, KSA will, currently, really max out your GPU if it can.
Finally, that leaves driver fault. Check that you have the absolute latest drivers installed. KSA runs a modern version of Vulkan, which is a graphics API. This requires the absolute latest drivers.