RAM required for comfyui

ive just started using comfyui and my pc specs are r5 5600x , 16gb ram and 5060 ti 16gb . the ram is almost getting to 100 percent and gpu utilization is only 3 percent . So my doubt is , do comfy ui first use ram and then start using vram and as i have only 16gb ram i couldnt run the workflow ?