Odd video issue with Pi 3


I got a Raspberry PI 3 from Pimoroni last week (and a ninja coupe pibow, of course) and have finally got to fiddle about with it. However, I’m having an odd issue - despite trying two monitors and two HDMI to DVI cables (one HDMI to DVI, one HMDI with a DVI converter plug) I keep getting an odd issue where the screen keeps blanking - in particular, the instant I run the browser or bring down the Raspbian menu it starts flashing on and off every second or so. I’ve tried fiddling with various config.txt settings (e.g. hdmi_force_hotplug and config_hdmi_boost - nothing seems to help, indeed increasing the boost seems to make it worse. On one monitor it even does it in hdmi_safe. I’ve tried a couple of PSUs with no improvement.

I’m starting to wonder if I have a faulty Pi 3 - is there anything else I could try?