What is ASW?
I will try this and report back.
When the frame rate drops a little (due to lots of detail, etc), the Rift software inserts synthetic frames using
ATW (Asynch Time Warp, Reprojection on the Vive). We've had ATW since launch - it handles the odd missed frame if your GPU is under heavy load and misses the deadline for display. ATW can't be turned off (no need and its lightning-fast anyway).
ASW is short for Asynchronous Space Warp.
Oculus included ASW recently - ASW is on by default. ASW detects when the frame rate drops consistently lower than (about) 80fps and locks the frame rate down to 45fps. This allows the GPU more time to complete each frame (up to 20-odd milliseconds compared to the 10-11ms allowed at 90fps). So with ASW running, you'll see the frame counter at 45fps, but you'll actually be seeing 90fps thanks to ASW, which looks for moving objects, uses the latest tracking data etc to render a synthetic frame in between each of the 45fps real frames delivered by the GPU.
ASW allows you to keep seeing 90fps - even if your GPU is less powerful (or in your GTX1080's case, is set to a pretty high detail level
).
I find I turn ASW off - ASW is in its early days and while its a great technology, it does have some drawbacks. ASW is squarely aimed at enabling lower-end GPU's to join the VR party, and not improve the experience of high-end GPU owners.
ASW does cut in pretty quickly (I think its about 75-80fps in ED) and stays turned on far longer than it should do (Ed seems to get stuck at 45fps in menus and stations etc even if you can render at 85090fps perfectly well once all the terxtures are loaded and nothings actually changing in the scene).
ASW detects the menus and panels, and the HUD as 'objects', and tries to re-render them when ASW is active. This makes little visible 'wiggles' in straight lines (like interference on an old TV), and the solid colour parts of the menus tend to bleed/melt. Text goes fuzzy too. ASW isn't perfect yet, and ED probably isn't set up to avoid the visual artifacts either.
Good thing is ASW can be turned off. Or on.
You can play with all four ASW modes:
ASW Off - Ctrl Numpad 1 - ATW only (preferred for ED for high-end GPU's)
ASW Off - Ctrl NumPad 2 - Forced 45fps (this can get uncomfortable and you soon see why 90fps is really necessary. Here you're simply at 45fps and A
TW is probably working overtime!)
ASW On - Ctrl NumPad 3 - Forced 45fps with ASW on, generating the
ASW Auto On/Off - Ctrl Numpad 4 - switches between ASW on and just ATW only modes by itself. This is the default, and tends to get a bit stuck (stuck on) in ED.
You can use these modes in any program, at any time - just make sure NumLock is ON. It starts out in Mode 4 (ASW auto on/off) each time you start a VR app. ATW and ASW still work if you run SteamVR app, although there is a small loss in performance.
Oculus' page explaining ASW is here:
https://developer3.oculus.com/documentation/pcsdk/latest/concepts/asynchronous-spacewarp/
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