I suggest you to use a ASIC miner such like Baikal or others, because Onion use X13 algorithm, the X13 ASIC miner has much more hash rate than GPU, you can get more profit. Though there is almost no profit even if you use the ASIC miner now to mine DeepOnion, you will get a huge reward in the future, trust me, because the price of onion will raise very fast and only the moon is the limit.