Thank you for your answer,
Yeah, i know electricity costs are really high.
I've also give a look to other gpus but this 3x 7950 seems to be the best in terms of ROI.
I've seen many "deals" for new gpus but they starts from 270€ and the ROI of a rig is higher, at least 3/4 months.
Are this the usual times when trying to build a rig from scratch?