I tried RivaTuner And It reported CPU usage of 20~25% but everything else is reporting 1% I wonder why?
Googling for an answer it seems mis-reporting CPU utilization has been a fairly common problem..both reporting too low and reporting too high. It's been a problem for several years and it's getting worse. It seems to occur for a lot of different reasons... from patches for various security threats breaking the way some utilities monitor to simply different approaches to actually measuring what "utilization" is.
Remember, high utilization doesn't mean the processor is working hard. It could be simply stalled waiting for some code or data, or working it's little heart out processing nested loops of intensive AVX2 instructions. Kind of like driving your car: you could be cruising along the freeway or stuck in traffic, either way it's 100% utilized.
Between those extremes are infinite possibilities that utilities have to be coded to report on. Some probably do a better job of it than others, and some pick an approach that a change in OS or drivers might easily break. Anything more precise is hard to say.