When enough time passes for RDNA to replace GCN, this will obviously happen seeing just how efficient RDNA is compared to GCN. After all, even with the efficiency-be-damned clocks of the RX 5700 cards they pretty much match Turing in perf/W (albeit with a process node advantage). If AMD makes their smallest RDNA die big enough, they could run it "slow" (say 1700MHz) for some excellent efficiency and make a kick-ass 75W card. Of course at this point this is all wishful thinking, but in time they will undoubtedly let RDNA trickle down to even the very low end. And if current rumors are anything to go by, it's on its way, though the rumored lower midrange Navi 14 (RX 570/580 replacement) will likely be coming out first.
Given that the "240W" (17A on the 12V rail, so 204W for all intents and purposes) PSU in my Optiplex 990 handles a "95W" i5-2400 and 150W RX 570, I'm not surprised. I'm working on getting a more powerful PSU in there, but so far it works fine, and pulls about 260W at the wall while gaming which translates to ~175W internal power draw (the PSU has an average efficiency of 65% — yes, it is garbage). That's when playing Rocket League or running Fire Strike. Gaming loads never hammer the CPU, after all, so power draw might not go very high. A 75W GPU and a reasonably efficient CPU should stay well below 180W combined power, even if I wouldn't run OCCT and FurMark on that combo.
Edit: this is the oddest thing ever, this post is about 2x the length in the editor, but only half the text is showing. Strange.
Edit2: Finally figured it out. A single "]" had gotten erased inadvertently. Have to stop posting from my phone.
