ATI : AMD Radeon HD 7990 Review

Officially canonized back in 2008 with AMD’s “small die” strategy, dual-GPU cards have since become a staple of AMD’s product lineup. Filling a small-but-important niche for AMD, dual-GPU cards allow AMD to both deliver ultra-enthusiast performance levels their traditional single-GPU products can’t offer, and at the same time compete with NVIDIA’s big die flagship cards without AMD needing to produce a big die GPU of their own. As a result, though these cards aren’t necessarily obligatory, with each generation we’re left eagerly awaiting just what AMD has in store for their capstone product.

Of course with that said, like so many other facets of the 7000 series, the dual-GPU situation has played out rather unusually in the past year. In a typical year we would see AMD release a standard design, and then later on partners like Asus and PowerColor would release their own custom designs in the name of product differentiation and squeezing out just a bit more performance. Instead the 7000 series has played out in reverse: Asus and PowerColor released their designs first. Consequently, up until this point the 7990 has been “officially unofficial”, reflecting the fact that the first 7990s were AMD sanctioned products, but not based on AMD designs.

But at long last the 7990 is becoming fully official. AMD is getting into the game with their own 7990 design, and perhaps more importantly they’re doing so while coming to bear with the kind of engineering resources that only a GPU manufacturer can provide. This isn’t going to be the first 7990 – that honor belongs toPowerColor’s 7990 – but this is unquestionably the most important 7990.  For AMD and their partners going official doesn’t just mean the AMD is taking a greater role in matters, but as we’ll see it means changing the rules of the game entirely.

AMD GPU Specification Comparison
	AMD Radeon HD 7990	AMD Radeon HD 7970 GHz Edition	AMD Radeon HD 7970	AMD Radeon HD 6990
Stream Processors	2 x 2048	2048	2048	2 x 1536
Texture Units	2 x 128	128	128	2 x 96
ROPs	2 x 32	32	32	2 x 32
Core Clock	950MHz	1000MHz	925MHz	830MHz
Boost Clock	1000MHz	1050MHz	N/A	N/A
Memory Clock	6GHz GDDR5	6GHz GDDR5	5.5GHz GDDR5	5GHz GDDR5
Memory Bus Width	2 x 384-bit	384-bit	384-bit	2 x 256-bit
VRAM	2 x 3GB	3GB	3GB	2 x 2GB
FP64	1/4	1/4	1/4	1/4
Transistor Count	2 x 4.31B	4.31B	4.31B	2 x 2.64B
PowerTune Limit/TDP	375W	250W+	250W	375W
Manufacturing Process	TSMC 28nm	TSMC 28nm	TSMC 28nm	TSMC 40nm
Architecture	GCN	GCN	GCN	VLIW4
Launch Date	04/23/2013	06/22/2012	01/09/2012	03/11/2011
Launch Price	$999	$499	$549	$699

Diving right into the thick of things, like the officially unofficial cards before it, AMD’s 7990 is a dual-Tahiti part, placing two of AMD’s flagship GPUs on a single PCB to make a single card. AMD has held nothing back and these are fully enabled GPUs, so each GPU has all 2048 stream processors, 32 ROPs, and their full 384-bit memory buses present. Joining these GPUs is 6GB of GDDR5 RAM, split up between the two GPUs for the 7900-series standard of 3GB of VRAM per GPU.

The big question with any dual-GPU card of course is what kinds of clockspeeds it can run at, and as a turns out the 7990 can clock rather high. The 7990 is a PowerTune Boost part like the 7970GE it’s based on, giving the card a base clockspeed of 950MHz, and a boost clock of 1000MHz. Meanwhile the memory is clocked at 6GHz, the same as the 7970GE. As a result the 7990 is surprisingly close to being a 7970GE Crossfire setup on a single card, clocked just 50MHz below AMD’s single-GPU flagship card. In fact this is better than some of the earlier 7990s such as PowerColor’s, which were clocked lower and simultaneously lacked PT Boost.

But perhaps the most defining aspect of AMD’s 7990, and the thing that sets it apart from unofficial 7990s that came before it is the TDP. AMD’s 7990 has an official TDP of just 375W, which although common for official dual-GPU cards, is quite a bit lower than the TDPs of the unofficial 7990s. As the GPU manufacturer AMD has the ability to do finely grained binning that their partners cannot, so while Asus and PowerColor have essentially been putting together cards that really are two 7970s on a single card – right down to the TDP – official 7990s get the advantage of AMD’s binning process, significantly reducing power consumption. The end result is that while an unofficial 7990 would be a 450W+ part, AMD can deliver the same or better performance while consuming much less power, putting the 7990 within the all-important 375W envelope that OEMs and boutique builders look for.

While we’re on the subject of power, this is the first official AMD dual-GPU part to include AMD’s ZeroCore power technology, which was introduced with the GCN family. ZeroCore as you might recall allows AMD to almost completely shut off slave GPUs when they’re not in use, which in turn allows AMD to further reduce their idle power consumption. The biggest benefits are found in multi-card setups since this allows the fans on those slave cards to be shut down, but even on the 7990 it still provides a benefit by allowing AMD to curtail their idle power consumption. Consequently this pushes the idle TDP of the 7990 down to around 20W, which is greater than a single card, but a clear improvement over 6990 and earlier AMD dual-GPU cards.

Moving on to product stacks and competition, it comes as no great surprise that AMD is placing their newest flagship part directly opposite NVIDIA’s flagship cards. AMD doesn’t produce a GPU equivalent to GTX Titan’s massive GK110 GPU, so the 7990 is AMD’s official answer to both Titan and NVIDIA’s own dual-GPU card, the nearly year-old GTX 690. In the case of the GTX 690 it’s a rather straightforward matchup since both cards are based on the same principles, while against Titan AMD needs to make a case about raw performance versus the inherent simplicity of a single-GPU solution over a dual-GPU solution.

Along those lines, since AMD is placing the 7990 against NVIDIA’s flagships they will also be pricing it directly against NVIDIA’s flagships, setting the MSRP for the 7990 at $999. This steep price tag raised some ire with the GTX 690 and with GTX Titan, and it likely will here once more. But with single 7970GEs still regularly going for $400-$500 and the fact that AMD is throwing in their best Tahiti chips into 7990, there’s little incentive to charge less. A 7970GE CF setup will be both faster and cheaper, but as a pair of those cards take up 6 slots after accounting for cooling needs, AMD can bank on the fact that the 7990 is essentially the same size as a 7970GE, charging a premium for the size advantage.

Ultimately customers interested in the 7990 will have a bit of time to sit on the matter and decide if they want one. The 7990 is being launched ahead of its actual retail availability, with AMD telling us the cards will hit etailers within two weeks. Meanwhile all of AMD’s usual partners will be participating on this 7990, so expect to see 7990 cards from all of major AMD partners, and sold at all of the major etailers.

Finally, AMD has been having a blast with game bundles over the last few months, and they won’t be stopping with the 7990. In a game bundle that quite frankly I cannot recall being rivaled by anything else done in the last 20 years, AMD will be bundling the 7990 with 8 different games from the current and past Never Settle bundles. All of AMD’s current bundle titles are included: Crysis 3, Bioshock Infinite, Tomb Raider, and Far Cry 3: Blood Dragon. Along with that AMD is also packing in the best games out of their previous bundles: Far Cry 3, Hitman: Absolution, Sleeping Dogs, and Deus Ex: Human Revolution. Simply put, 7990 buyers will be well-stocked for games to play on their new video card.

Meanwhile on housekeeping note, AMD will be changing how vouchers are distributed for the 7990; rather than having etailers distribute the vouchers with qualifying purchases, AMD’s partners will be packing the vouchers into the product box. Though the etailers have been good about including vouchers, they do at times forget them. So for the 7990 AMD and their partners aren’t going to be taking any chances.