I've got a 6870, and it mined about two LTC/day before the difficulty went up very recently. Maybe 1.5 now. That's about $4.5/day at current rates (which are currently falling).

It's all very uncertain, so don't expect to get a positive return on your investment. You might. You might not. It's a gamble, and calculating the odds is nearly impossible

As for your other questions: the wattage is fine, the other hardware isn't important, Linux is fine.

I'll throw in another vote for p2pool, it works like a charm. I just set up my own p2pool, feel free to give it a spin if you want to get a feel for how it works (or keep using it for that matter). Keep in mind that you'll have to keep mining for 24-36 hours to get your fair share, so don't get discouraged by low payouts at first.

Dummy plug in one of your ports?

AMD produces the chips and reference designs, and companies like Sapphire, XFX and others make the actual cards you can buy.

But if you're thinking of buying a GPU strictly for mining purposes you better work out the math first. It may take you a long time to get your money back. Also keep in mind that the difficulty is likely to increase quite a bit now that ASICs are getting deployed.

I'm honestly not trying to be an ass here, but you answers are pretty easy to find:

http://lmgtfy.com/?q=litecoin+mining
http://lmgtfy.com/?q=buy+litecoins&l=1

All of the hard work is done in OpenCL kernels anyway, so unless your language's OpenCL libraries suck I don't see why there would be much of a difference.

CPU mining is dead, forget about it. If you don't have at least a decent GPU there's no point in mining.

You don't really need a calculator

The advertised TDP of a 6870 is 150 watts. That's 3.6 kWh per day if you run it 24/7. Multiply that with your effective cost of electricity per kWh and you've got an estimated daily additional electricity cost.

Example: If you pay 10 cents per kWh, your daily cost is approximately 3.6 * 0.10$ = $0.36/day.

Hi!

I've been on the fence for far too long when it comes to cryptocurrencies, but I've finally gotten my butt in gear now and started mining some Litecoins on my 6870 today.