Constant rate frame drop

Hello,

I have a strange problem with the SDK 0.6.0.1 and a Oculus Rift DK2 device:

Sometimes I have very constant rate frame drop (about 1 per second) leading to a bad user experience.

In some case, i have a constant frame drop and it can last during all the demo execution. In the OculusWorldDemo, it persist even disabling the multisample, reducing the pixel density to 0.1 or set the minimum FOV.
In others cases i can have no drop at all, or no drop during few seconds then 4 or 5 random frame drop always spaced by about 1 second.

http://i.imgur.com/pCvSfGJ.jpg

I check kernel latency and it seem ok:

http://i.imgur.com/tBtYArr.png

I check with GPUView and there is very regular 25 ms gap in the graph.

http://i.imgur.com/aFZEiuD.png

I measure the timestamp of the gap and for about 20 gaps the duration between 2 gaps is always between 1012 ms and 1086 ms (mean: 1045 ms).

I also test with OculusTinyRoom D3D and even if i don't see drop, if i perform a trace with GPUView it still have a gap each seconds, but 10 ms instead of 25 ms.

I don't find any gap with GPUView with the OculusTinyRoom Opengl demo.

Do you have an idea of cause of these anoying frame drop ?

(I use a Nvidia Quadro K2000M v348.27 with Windows 7 SP1)

Thanks !