Alexandre, by 970 you mean the GEFORCE GTX970? That is an old GPU and not good for daggerhashimoto (ethash). To mine ethash you should have a RX570/580. But even with that and a modified GPU at the moment you can achieve only about 1 USD per day for 1 card.... On any other algorithm like cryptonight or equihash it will be even less. particularly with one GTX970.