I was actually thinking since I am a gamer and my machine already old, I will get 4X7970s running in Quad-Crossfire, actually put on a decent ram and CPU anduse it for gaming and have it mine novacoins and litecoins in the meantime. If it pays for itself in a year that way, I would be pretty happy with that. Unfortunately, I do pay for my own power. Also, I see everyone saying 7950s, but what about 7970s or even the new 7990s?
This is what I'm doing. I have 2x7970 that I use to mine litecoins while not gaming (and my electricity is included in my rent for the moment
![Cheesy](https://bitcointalk.org/Smileys/default/cheesy.gif)
).
The reason everyone recommends the 7950 is because they are cheaper and have mining performance equivalent to the 7970 (although for gaming the 7970 is better). As for the 7990, it seems to have a speedup of around 2x compared to the 7950/7970, as one would expect.
Some helpful links:
https://en.bitcoin.it/wiki/Mining_hardware_comparisonhttps://github.com/litecoin-project/litecoin/wiki/Mining-hardware-comparison