well, usually GPUs come with cooling solutions, either passive or active ones such as heat sinks/ fans/ even water coolers. There are also aftermarket coolers for graphic cards and you can usually find water blocks for reference cards which enables you to add them to your water cooling loop. Some people have gone as far as rigging up CPU AIO coolers to work on GPUs or use CPU heatsink/fan coolers on GPUs. I guess it really depends on your actual setup and what you are looking to achieve.