It can be normal, depending on the game/resolution. At 1280x1024 in old games the GPU does not have much work to do. I tried running Crysis at that resolution and it was running at 800MHz.
I'm not sure what game that is, but it looks like you could run it at 4K with no problem.
Try running a benchmark like Unigine Superposition. If your clock still stays below 1000MHz then you have a problem.
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