As you can see we managed to achieve 1100MHz stable. In fact, our overclock took us all the way to 1140MHz, but games would lock up instantly when started. It wasn't until we got down to 1100MHz that games would run just fine. Since the default frequency is 1018MHz that is an 82MHz overclock. 1100MHz is the best overclock we've ever achieved on a 290X GPU without voltage tweaking. It seems the water cooling definitely helps. There is headroom to overclock higher thanks to the cooling. We experience a maximum temperature of 71c at 1100MHz. With some more voltage we could see these GPUs being stable at higher frequencies and maintain temperatures in the 70's. However, we did notice one thing, in Overdrive there was a maximum temperature cap of 75c. Therefore, without special supported software we may see the temperature max out at 75c and keep us from overclocking beyond that.
Time will tell how that works out, and once we can overclock with voltage overclocking that is when we think overclocks on the R9 295X2 may be impressive. By adding another fan on the radiator we may even be able to keep the GPU cooler, and thus achieve an even better overclock with voltage overclocking. In the end, we think the R9 295X2 has potential for being an enthusiast friendly overclocking video card with some extra potential thanks to the water cooling setup.