If there was a single best coin to mine, everyone would be mining it all the time.
Depends on your situation and what's available around you.
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well, that makes sense
a friend of mine recommended mining ETH
6 AMD GPU generates hash power
is that correct?
Since you are in free electricity, that 6 GPU of course will give you profit, even, whatever device you are using, you still profit.
If I want to mine litecoin , which GPU do I need ? lets assume i bought 6 of them what else do I need? motherboard + Rams + power supply ....etc ?
You can mine LTC with GPUs Rig, but you'll get nothing since LTC (srypt-based) has an ASIC Miner such as Antminer L series. If you plan to mine Litecoin, better to buy ASIC miner. ETH or another coins/Algorithm without ASIC miner on it, GPUs seems fine with your condition.