Hey guys I just built mining rig in Bangalore....I do not know when I reach ROI

... here's my specs
6 x 1070 Geforce G1 gaming rev 2.0 GPU
MSI Z270-A Pro motherboard
6 x Riser cables
Kingston 128 SSD
4GB Ram
1000 Watt Crosair PSU
Total around 2.8 Laks
I've a problem here., I can mine with only 5 GPUs...when I connect 6th GPU however windows detect all 6.. but when I start claymore I get CUDA Error...
Can someone help me with this please.
Thanks
Happy AltCoin Mining !!!