Power, Temperature and Noise
You didn't expect anything different? Two Radeon R9 295X2 cards are too much for a 1kW PSU to handle. The Grid Autosport test isn't as hard on multi-GPU graphics cards as, say, Crysis 3, where at-the-wall figures of 1,206W were observed. Taking the overclocked Core i7-5960X into account even a high-efficiency 1,300W PSU is cutting it reasonably close. The comparison WaterForce pulls 619W in the same Crysis 3 test.
Thirstiness in the wattage department usually means sky-high temperatures. AMD's all-in-one watercooling works very well in a single-card setup and almost as well when two R9 295X2s are installed into a powerful system.
Two cards use a total of four fans to keep the Hawaii GPUs relatively cool under load. The combined noise isn't as piercing as the single reference R9 290's, which is plain annoying. Rather, the fans produce a noticeable but steady whooshing sound. Gigabyte's WaterForce is fundamentally quieter in this regard.
