That's 35.625V per cob. Check the graph again and look up the voltage at 1750mA. Looks close enough to datasheets to me.
Measure after an hour again when your cobs get to working temperature (case temperature of the package). You start at approx 25°C as this is probably your room temperature or maybe even lower. With the measured voltage you can determine at what voltage each individual cob runs or even better, measure each individual cob, and after looking at that graph you can calculate the temperature and get the power your cob is using. Some run as low as 27W/sqr' some run higher powers like say 35W/sqr'. Id look up some grow diaries and decide what would work for me.
If you ask me, run them bitches at nominal power with sufficient cooling. So 90W for a 3590.