The 'zero gpu activity' may be a clue that the gpu isn't involved - the slow performance is due to using the CPU only. Is there some setting in the application that addresses recognized GPUs? A GPU has to be explicitly selected in some apps.
I guess that you've installed the universal pro driver from AMD, but really have to mention it in the checklist sense. The W5000 didn't come with a driver and I had to search out the latest pro version. Do the W8100 and monitor and their driver versions show up correctly in Windows Device Manager?
My W5000 advances to PCIe3 very rarely, using PCIe2 or 1.1 for most activities. I'm quite satisfied with it in the apps I use, given that it's two steps smaller and a gen older than the W8100.