Be aware when overclocking the GTX 980 Hybrid or a GTX 980 with the Hybrid upgrade kit, the stock blower fan is still used to cool the VRMs and memory on the card. The blower fan speed is based off of the temperature of the GPU, and as GPU temperatures with be far lower than with just the stock cooler, you may need to set a custom fan curve or manually increase the fan speed with PrecisionX to keep these parts of the card cool while overclocking. If you experience instability or artifacting while overclocking, try increasing the fan speed and see if that resolves the problem.