Was building a new machine and you can tell I haven't done this in a long time. Went with Ryzen 5 2600X and a decent motherboard with dual HDMI ports. I also added 16gig of ram. I thought because I'm a Linux user and don't do much graphically intensive work I will be fine using the internal graphics. I do video editing, but under Linux, most of the heavy lifting is still on the CPU so I thought I had a decent selection. Parts arrived and it went well. Pieced it together in about an hour and then for the moment of truth...
Trying removing ram in turn, same result. Double, triple and quadruple checking all connections still nothing. One quick Google search let me to the depressing discovery that with Ryzen not all processors support video. I knew the new Ryzen chips had moved away from the CPU/GPU hardware and provided both from the processor (APU). I just didn't realise not all Ryzen processors supported this.
Long story short I am keeping the CPU because 8 core 12 threads will be great for Linux and will install a separate GPU (mid-range). Guess we live and learn.