AMD's Radeon R9 295X2 is an impressive piece of engineering. AMD managed the seemingly impossible: to cram two fully unlocked, fully clocked Hawaii GPUs onto a single graphics card. AMD's ace is the watercooling solution from Asetek, which, despite being relatively compact with just a 1x 120 mm radiator, can handle the heat both GPUs put out quite well.
In terms of performance, we see truly impressive 4K resolution numbers from that are essentially twice those of a single R9 290X card. With these results, the R9 295X2 is the fastest single card solution available today, and a great choice for this resolution and 5760x1080 EyeFinity. Thanks to the low temperatures provided by watercooling, the card does not throttle during normal games, which leaves its full potential at your fingertips at all times. Yet unlike a single GPU card based on two graphics processors, the R9 295X2 needs good drivers to show proper performance improvements in games, and AMD's updated driver support produced better CrossFire scaling across our test suite than ever before. The only game that does not scale properly is Diablo 3: Reaper of Souls, which marks a significant improvement over the last time we looked at CrossFire with the HD 7990, where six out of eighteen games did not scale as expected. It still shows that you may be left with single GPU (R9 290X) performance when a new title comes out for which CrossFire support is not available immediately. Also, at lower resolutions, 2560x1600 and below, scaling is slim in general, and I would not recommend the R9 295X2 or any other multi-GPU solution for those setups. A powerful single-GPU solution, like NVIDIA's GeForce GTX 780 Ti or Titan, will definitely do better at 2560x1600 while being more cost efficient.
In order to keep their card at sane temperature levels, AMD opted for a watercooling solution by Asetek, one of the leaders in this field of technology. The Asetek watercooling solution works flawlessly, comes prefilled, and is self-contained and maintenance free. You only have to install the card, find a spot for the radiator, and power it up. You'll hear some noise due to air bubbles circulating in the loop, but it'll disappear in a matter of minutes, and the two pumps (one for each GPU) are almost inaudible. Nevertheless, watercooling always introduces more complexity into a system, which could be troublesome in smaller cases. At full load, the watercooling radiator also gets quite warm; you won't burn yourself, but it will feel hot to the touch. The 500W+ heat output will definitely warm up your room, and there is no way around it as the heat has to go somewhere. While many might say that the 120 mm radiator is too small, it does a fine job and keeps the card at good temperatures, but does so with a little too much noise. Temperatures under load are around 60°C, so AMD could have, in my opinion, run the fans slower to reduce fan noise.
A second fan is installed on the graphics card itself, and its job is to cool voltage regulation circuitry and memory chips. This fan has to work incredibly hard and tends to be noisy. I also wonder whether this part of the thermal solution is designed properly. Under full load, our new thermal imaging camera reveals that the backside of the card reaches over 100°C as heat produced by the VRM circuitry on the front travels through the card, which means the components on the front are even hotter. Taking a closer look, it seems as though the heatsink fins under that fan are facing the wrong way as they direct air to the sides and onto the walls of the waterblocks instead of up and out. AMD should have maybe used a single, full-cover block that cools all components to avoid such problems.
Another surprise is that the card still produces some coil noise (listen for the chirping noises in our thermal imaging video). While less pronounced than with the HD 7990, it is still there. After all the HD 7990 drama, I expected AMD to make absolutely certain it wouldn't happen again. Depending on the situation (FPS, game, and load), coil nose also changes in both volume and frequency, which, at times, makes it incredibly distracting and very difficult to ignore. I find the R9 295X2's acoustic footprint higher than what would be necessary, especially in idle. The card runs at noise levels comparable to other high-end cards that are obviously slower under load, but I feel AMD could have optimized things a bit better. With current drivers, the card has absolutely no fan control or fan speed monitoring, so you can't even just adjust things on your own.
Now, let's look at power consumption. As expected, power consumption is high, really high. The R9 295X2 generously sips power in even non-gaming states since the two pumps and fan on the radiator require power at all times. You should expect around 500-600 W of card-only power draw while gaming, which means that you can't cheap out on the power supply. 750 W is, I'd say, the absolute minimum, and 900-1000 W is better if your other system components are high-end too. AMD is overdrawing the PCI-Express 8 pin connectors. Instead of a maximum of 150 W per connector, they are pulling more than twice what is allowed in the specification. While it's not uncommon for overclockers to do so, I'd like to see a third 8-pin connector instead. And yes, the power cables get warm to the touch. Looking at performance-per-watt figures at 4K resolution, the R9 295X2 actually doesn't do too bad as it is about 15% more efficient than the HD 7990, which roughly matches the GTX 680, but NVIDIA's high-end models are up to 20% more efficient.
AMD is asking $1500 for the R9 295X2, which is simply too much. Right now, the R9 290X retails for around $570, so I don't see a reason for AMD to charge $1500, other than "we can because NVIDIA charges more". A more reasonable price for the card would be one below $1000, around the $900 mark. It's not the second coming of Christ and still has some technical difficulties, but its performance at 4K is simply impressive. Given NVIDIA's announced $3000 pricing for the Titan-Z, which I doubt will be much, if any, faster than the R9 295X2, the R9 295X2 suddenly looks affordable. But if I were to build a 4K gaming system, I'd just use good old CrossFire and SLI to build my rig with R9 290Xs or GTX 780 Tis for a much better price, which would nearly net me a 4K monitor for free. I'm not so convinced that 4K is a must anyway as I see very little difference between 2560x1600 w/ AA and 4K w/o AA in most games, so little that I wonder whether the performance hit is really worth it.