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60W is impressive...

Does not even have external PCI-E power connector.

It might look impressive compared to older generations of AMD GPUs, but with the new ones it is pretty much on on par with what other RX series vidoe cards do in terms of power usage/performance ratio.

Is that using the 2GB or 4GB variant?

2GB, though it should not make a difference between 2GB and 4GB performance wise.