In the end of 2013, the ROI of a GPU was 30-40 days... OMG I miss these days...
I remember that my Radeon HD 7850 1GB was making $8/day on Dogecoin while it only cost $200. I really miss those days. Back in the day, you could also mine Ethereum on 2GB video cards. I also remember when I mined BTC in early 2013, but revenue was slashed by half in just one week. The 1st gen ASICs were being released.
At least the upside is that the industry is more mature, so there's less risk, but less risk means less reward.
Yeah I had that GPU. It was slow but you can get it for almost nothing if you monitored the Craigslist listings all day. I think I bought one for like $50.
It was basically a low clock rate Radeon 270x pretty much. I think the regular 270x hashed at 450kh/s while the 7850 hashed at 375-400hs. However you can score them second hand for like $50 compared to paying $150-175 for a new r9 270x.
The king mining GPU back then was the r9 280x (290 was just released and not popular) and those suckers put out something like 700kh/s and burned 350 watts EACH.
I remember having 2 GPUs per PSU and each PSU was using 700watts. Crazy times. Even with all that power consumption they never really ran hot actually.