Yes, you can mine Ethereum with an external GPU. While it is possible to mine Ethereum with a CPU, it is not recommended as it is very slow and not very profitable.
GPUs are much faster and more efficient at mining Ethereum.
NOTE: Warning: Mining Ethereum with an external GPU is not recommended. External GPUs come with many problems, such as limited power supply, noise, heat, and lack of adequate cooling. Additionally, mining with an external GPU can be less profitable due to the increased cost of electricity and hardware. If you decide to mine Ethereum with an external GPU, it is important to research the best hardware and cooling methods for your setup.
The biggest advantage of mining Ethereum with a GPU is that it can be done relatively cheaply. GPUs are readily available and can be purchased for a few hundred dollars.
Additionally, they do not require a lot of power, so your electricity bill will not be too high.
The downside of mining Ethereum with a GPU is that it will take longer to see a return on your investment. However, if you are patient and do not mind waiting a few months, you will eventually start to see some profits.