I am having very similar problems, though I have managed to minimize the audio drop-outs. I think that I have narrowed it down to a 'Killer' networking device, as when I run LatencyMon and browse the web, I get 'buffer underrun' warnings of varying severity.
I have tried installing various different versions of 'Killer Suite', and driver only versions and while some are better than others in terms of latency and stability, none solve the issue.
Just now, I literally set all of the features on the network card that were 'enabled' to 'disabled', through the advanced tab on it's properties on the device manager (control panel, device manager, network adapter, properties, advanced), changed it to '100Mbs full duplex' and increased the 'Max IRQ per second' to 15000 and left the other values the same.
25 mins and no DPC spikes...Yet. I haven't tried Cubase yet, though. Just thought that this might help you. Worth a try.