I have tested the hybrids extensively, 980, 980TI and TitanX.  When clocking the GPU the hybrid block itself will handle that, however since natively the blower fan is tied to GPU temp it will not ramp up much, which does limit the upper end of overclocking with everything at Auto.  manually crank up the fan or use a fan profile.  You will need to do some benches at stock and with a mild/moderate overclock on the GPU to see where yours sits at under load.  For the one here at my test bench, I had a sliding scale from 30-35-40-45c bringing the fan RPM from 40%-60%-80%-100% at those speeds that way the VRM was being cooled well, it did allow me more headroom on my overclocking.