http://cryptomining-blog.com/8526-mining-performance-of-gtx-1080-ti-with-ccminer-2-0-rc2/ So 7 of the GTX 1080 ti will pull close to 150 MH/s - but at 1750 watts JUST for the cards, figure close to 2KW for an entire single rig if you can get all 7 running on one rig.
There's also the issue that the 1080 ti is ONLY available in founders edition (so far), at a significant premium on price, and VERY limited availability - and running the calculation for 7 or these on whattomine at the stated figures in the post show them LOSING MONEY if you have to pay more than 1c/kwh on your electric.
On the other hand, this is actually PROFITABLE up to about 10c/kwh electric - but nowhere near as profitable as mining ETH would be on those cards, much less something they're GOOD at like lyra2r2.
I wouldn't use the 1080's but rather the 1070's... You can pull about 420 S/s per card for zcash and for a 6 card rig you could get the wattage down to about 1000 in total if you configure it properly. ROI on one of these rigs would be 6-8 months dependent upon price but at least you can purchase all of the parts anytime you wish unlike with Baikal right now.