>> Having 120hz refresh is a good improvement over the Rift prototypes, but
>> it should really have a variable refresh rate to match with the graphics
>> output (like the nvidia gsync system) to minimise lag when the GPU can't
>> keep up with exactly 120fps.
>
> Bad, bad idea. That'll make your image appear to jitter when framerate
> drops. Headaches guaranteed.

Strange, apparently it signficantly reduces the jitter and lag when the 
GPU can't quite render at the monitor refresh rate. AIUI the way it 
works is if your monitor is capable of 144 Hz (as most gsync monitors 
are) and you're in a busy bit of a game and the GPU can only render at 
(say) 100 Hz, then instead of jumping between 72 and 144 Hz continuously 
the monitor will refresh at a steady 100 Hz to exactly match the GPU. I 
believe in VR lag is one of the main things that gives you headaches, so 
the fact that the display is exactly in sync with the GPU should improve 
things?

> Better have the GPU render to an interim image buffer (possibly at low
> framerate), and have a separate thingumajig do high-speed fixed-rate
> mapping of that interim image buffer to the VR display, taking into
> account the extrapolated direction you'll be facing the very moment the
> image will actually appear.

I think I remember reading thet top nVidia cards do that already, they 
just use the actual previous framebuffer at full resolution and shift it.

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