Does OpenCV 4.x dnn module has OpenCL support for NVidia or AMD GPUs

Gaming and Visualization Technologies General Topics and Other SDKs Drivers - Linux, Windows, MacOS
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I am trying to run a DNN model using OpenCV on NVUDIA GPUs. Cuda Works fine. I am trying to run models using OpenCL.

network.setPreferableBackend(cv::dnn::DNN_BACKEND_OPENCV);
network.setPreferableTarget(cv::dnn::DNN_TARGET_OPENCL);

I got lower fps than the CPU. The task manager shows no increase in GPU usage. Does the OpenCV dnn module utilize NVIDIA GPU if I select OpenCL?