AMD Radeon HD 7990 6 GB Review 156

AMD Radeon HD 7990 6 GB Review

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Value and Conclusion

  • According to AMD, the HD 7990 will retail for $999 and should be available in two weeks.
  • Extremely fast in games that scale
  • Fantastic game bundle included
  • Backplate included
  • Good additional OC potential
  • Four DisplayPort outputs, up to five monitors total
  • Reasonable fan noise, given its performance class
  • Supports voltage control
  • Can do CrossFire with any other Tahiti-based card
  • Dual-BIOS feature
  • High price
  • Annoying coil noise
  • Requires CrossFire game support to reach proper performance
  • Many games do not scale properly in CrossFire
  • Very high multi-monitor and Blu-ray power consumption
  • Slim performance gains from overclocking
  • Long card
Finally! AMD's Radeon HD 7990 is here! We've been anticipating the release of this card since the HD 7900 Series was introduced, and since NVIDIA released their GeForce GTX 690 flagship almost a year ago. The company's new card is built on the foundation of two full-fledged Tahiti GPUs that come with all shaders unlocked. Both also run at up to 1000 MHz, which almost matches the clock speeds of the HD 7970 GHz Edition. Our performance testing reveals excellent performance results in those games where CrossFire is working as intended, making the HD 7990 the fastest graphics card in the world in these cases. Recent titles like Crysis 3, Tomb Raider, and Bioshock Infinite show good scaling that easily surpasses the performance of competing cards, like the GTX 690 and GTX Titan. However, we've also seen many games that do not scale well, and they make up a significant portion of our tests. Out of eighteen titles, five did not scale, or worse, showed negative scaling. These are not small titles, but big AAA games: Assassin's Creed 3, Batman: Arkham City, F1 2012, StarCraft II, Skyrim, and World of Warcraft. What really surprises me is that this long list is the same as the one we had with our reviews of HD 7990 "New Zealand" implementations by board partners, like the ASUS ROG ARES II and PowerColor Devil 13. So either AMD does not care or can't fix CrossFire support with these games millions of people play.
To look at things from a different perspective, we created a second set of performance summary graphs that excluded all these problematic games, representing a scenario better suited to CrossFire usage, but the HD 7990 still only managed to beat the GTX 690 by 6% at 2560x1600, which is hardly a convincing result with the scaling issues looming in the background. Some people might argue that we could see better CrossFire scaling in the future because AMD graphics technology will power all future consoles, but I'm not so sure about that. Console developers don't develop for CrossFire and are happy that they only have to support a single hardware configuration.

Power consumption of the HD 7990 shows surprisingly good results that have clearly improved over dual HD 7970 GHz Edition or ARES II/Devil 13 setups. The major foundation of these improvements seems to be due to AMD's tight selection of graphics chips with low leakage. The Boost clock and PowerTune algorithm doesn't appear to be any different from the HD 7900 Series. The card runs 1000 MHz when it can and drops clocks down to 950 MHz when it senses a power overload condition. In our testing, we see this happen quite often, and in most games, the card definitely doesn't run at 1000 MHz most of the time, which results in a significant performance loss. AMD also had to pick our sample up after less than a week to ship it to another reviewer, which could be an indication of how scarce these binned GPUs are.
Non-gaming power consumption is improved over the last generation's HD 6990. AMD's ZeroCore power technology, which puts the second GPU to sleep outside of gaming, is useful here. Nevertheless, the card is not nearly as power efficient as products by the competition, especially when it comes to multi-monitor and Blu-ray power consumption, but that's a general AMD problem.

The large triple-fan cooling solution does a good job at keeping the HD 7990 cool; the card's reduced power consumption definitely helps keep temperatures in check too. When I first saw the three fans, I was immediately worried about noise levels, but AMD quickly mentioned that the card is "whisper quiet". While our testing clearly contradicts "whisper quiet," the card is not that much noisier than the GTX 690. Idle noise levels really are whisper quiet, just like with the GTX 690, GTX Titan, and any other modern card with reasonable fan-speed settings. What is a major issue, though, is the extremely annoying coil whine the card emits as soon as it runs a 3D application. The whine is generated by resonating power circuitry coils and is a problem that can be resolved; it's just an engineering challenge. NVIDIA did so for the GTX 690 and GTX Titan; both cards don't have such coil whine issues. On the HD 7990, however, it is very apparent, and I don't understand how AMD missed such a glaring problem. I talked to five other reviewers and they all confirm it, so it's not an isolated issue. What makes the whine even more apparent is that it is constantly changing pitch and volume, drawing your attention to it by effectively overpowering the fans' "whoosh" sound.
The HD 7990 cooler itself is well made, but is still, unlike the GTX 690 and Titan, made of plastic, which doesn't give it that ultra-high-quality feel of competing products. I do have to commend AMD for including a backplate with their card, which also protects against physical damage.
Overclocking on our sample worked well and reached 1130 MHz, which is nowhere near the 1200+ MHz we see on single-GPU HD 7970 cards, but 1130 MHz still shows that decent clock headroom exists. In terms of real-life performance, the 11% clock only translated into 4% higher framerates, because the card quickly ran into its power limit and dropped clocks to 950 MHz. Thanks to a Volterra VRM design, voltage control is possible and not limited by the driver (like on NVIDIA cards). This should make the card interesting to hardcore overclockers. Our testing on the stock air cooler showed disappointing overvoltage results, though. The card heated up very quickly and ran into a power or heat limit that made any further voltage increases redundant.

In terms of pricing, AMD matches what NVIDIA is asking: $1000. AMD does include eight free games with the card: BioShock Infinite, Tomb Raider, Crysis 3, Far Cry 3, Far Cry 3: Blood Dragon, Hitman Absolution, Sleeping Dogs, and Deus Ex: Human Revolution. All of them are good games and definitely worth playing. You could also pawn them off on eBay to offset the cost of the card; getting $100 that way should be really easy. Still, even at $900, the card feels too expensive to me, especially when compared to NVIDIA's offerings. The GTX Titan comes at the same crazy $1000 mark, with significantly lower performance, but its unique feature is that it uses a single GPU, which means that any game will scale, no matter how broken its multi-GPU profiles are. The GTX 690 uses two GPUs, just like the HD 7990, but provides much better scaling in more games; and neither NVIDIA card has the annoying coil noise issue I mentioned earlier. For me, a reasonable price for the HD 7990 in its current state would be around the $800-$850 mark (with the included games).
In order to overcome the frametime issues some of our colleagues reported, AMD is working on a new driver to improve things, and has provided us with it, but it's only for Windows 8 and sacrifices some performance for more constant frame delivery. We also had no time to test it because our sample had to move on, but I expect AMD will eventually figure out how to solve this card's problems. It does make me wonder why AMD had to release the HD 7990 now instead of waiting just a little bit longer, which would have given them the time to solve the frametime and CrossFire scaling issue and, last but not least, get rid of the coil whine.
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