There appear to be 2 versions of the external power supply, one at 135W and one at 200W: http://www.storagereview.com/hp_introduces_the_z2_industry_s_first_mini

There appear to be 2 versions of the external power supply, one at 135W and one at 200W: http://www.storagereview.com/hp_introduces_the_z2_industry_s_first_mini_workstation http://www.storagereview.com/hp_introduces_the_z2_industry_s... The supported E3-1270, 1275, and 1280 are rated at 80W. I'm not sure about the M620 GPU, but since it's the successor to the 45W K620, that might be a good guess. If they need to offer the 200W version, I assume they will occasionally need to handle at least 135W of cooling inside the chassis.