And yes they are power hungry. For ETH it used 200 Watts which is considered too much by todays standards however back in 2014 I mined with many of these 280X mining Litecoin and guess how much power they used??? For a 2 GPU rig so 2 * R9 280X the power at the wall was over 700 Watts. Even if you undervolted it still used tons of power.
Basically a single 750 Watt PSU could only power 2 GPUs.
For Ethereum, this was quite enough, but the memory of these video cards was 3 GB, so the R9 280X was replaced with other video cards.
I liked the R9 380 and R9 380X better because they were cold.
Yeah back in late 2015...early 2016 I had a huge dilemma. Basically the only GPUs that I was in the market for were the R9 280X or the R9 380. Both of them cost almost the same... maybe the R9 380 a little more.
Here is the thing. When the ETH DAG was very low, the R9 280X mined at like 26MH/s or so. The R9 380 mined at like 21-22MH/s. So I basically decided to get the R9 280X instead. Spent most of my budget on those... big mistake.
Why? I didn't realise that the R9 280X would slow down on each new DAG, eventually from 26MH/s it mined at 21MH/s, same speed as R9 380 however the 380 never slowed down but the 280X. Something called DAG Thrashing bug.
So if I bought the R9 380, I could of mined longer and because it was 4GB even longer that the 3GB 280X.