Compositor can't meet vsync deadline - stuck at 45Hz

[mm0zct]

I'll preface this by saying I am well aware that my pc does not meet the minimum specifications, and I'll be doing some experiments with a friend's components soon to see what I can get away with not upgrading just yet (I'd like to hold out for Polaris/Pascal on the GPU front, and see what Zen has to offer if I have to replace the CPU too).

With a clean install of Windows 10, and only the Oculus Home software and Virtual Desktop, the Oculus Home and VD applications work fine at first. However after a while I start to get a split-vision effect. Looking at the debug output enabled by VD it seems that the Oculus Compositor is missing it's 90fps vsync deadline, and so I am getting each frame displayed twice. Because the display is strobed, rather than persistent, I see a double image rather than a blur which I would have had with my DK1.

I could accept this as being because my system is underpowered, were it not for the fact that VirtualDesktop is rendering at a solid 90fps, and no single core is over 25% load, while the GPU is basically idling and is not even rising it's clock frequency.

I have set the frame rate target in the AMD control centre to 90fps with no effect and am using up to date drivers. The issue was the same in Windows7, which is why I switched to try a clean Windows10 install. Sometimes it starts hitting the 90fps frame time if I look over to the right in Oculus home and the stutter/split vision goes away, but comes back when I look back at the floating menus or the floating cubes to the left.

My system is an AMD Phenom II 1055T (6 cores @2.8GHz) with an AMD 7870 and 8GB of RAM. I have the Innotek USB3 controller with no hubs.

Has anyone else seen this issue, or have any idea what could be causing it? I'll post my log files next time I'm on the PC.