I've literally just installed my new Powercolor Liquid Devil 6900 XT, in my X570 motherboard with my Ryzen 5900X, and immediately have a problem. I loaded up X-Plane 11, my favourite simulator/game, and was presented with 22fps at 3440x1440p. On investigation, the GPU SCLK never gets above 1000mhz in X-Plane. When I run the 'stress test' from within the Radeon software, the GPU then gets up to the maximum clock. It's like it doesn't recognise that X-Plane requires it to operate at maximum performance. When I run the Heaven Benchmark, the GPU clocks up and down as necessary to maintain the 60fps needed.
Any help would be much appreciated. I've never had an AMD GPU before and this is especially frustrating!
What is the CPU and GPU usage at this time? Per-thread CPU usage is important to know as well, which you can find by downloading Process Explorer and opening the properties of the game process, switching to the Threads tab, and sorting by CPU usage descending.
It's hard to imagine a 5900X is causing a CPU bottleneck, but that's the general reason why the GPU doesn't clock up as high, so it needs to be ruled out.