the HP z series workstations are not like clone consumer based systems. as such you can not use their methods of determining the needed power supply wattage
unlike most newer consumer systems the hp workstations use a power supply that is a multirail design a not single rail
as such the listed wattage for each listed rail on the supply is the MAX it can deliver. if you exceed that the supply will shutdown
a single rail supply on the other hand is capable fo delivering the units max rated wattage on any voltage, which can be bad if the unit develops a short as all amps will be available!!
pull the power supply out, look at the 12v GPU wattage listed on it's label that is it's max
the 1100 watt supply is able to power a 1070/10 80, as these are 180 watt cards the 1070TI is a around 220 watts
which is within the 1100 watt supply ability.
your card is allready overclocked, there is no guarentee that it will reliably overclock even more.
any overclock risks damaging the card, and the gains from a overclock will only be 1-3 frames which is a poor return
when you risk the card for that small gain