What mining card would be best for mining?
GIGABYTE TECH GTX 1080 TI 11GB GDDR5
ASUS TURBO GTX1080TI 11G / geforce gtx 1080 ti 11gb gddr5x pci-e 3.o
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Both cards are GTX1080Ti so the difference will be negligible at the same power consumption
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Also could i use an "old" i7 desktop pc to start mining or would you suggest getting a new motherboard +cpu as well?
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Old MoBo, CPUs are good enough for mining - no problem
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Is there a startup guide for mining noobs?
There are many, just google it