Original Link: http://www.anandtech.com/show/4260/amds-radeon-hd-6790-coming-up-short-at-150



The last couple of weeks after the recent GeForce GTX 550 Ti launch have been more eventful than I had initially been expecting. As you may recall the GTX 550 Ti launched at $150, a price tag too high for its sub-6850 performance. I’m not sure in what order things happened – whether it was a price change or a competitive card that came first – but GTX 550 Ti prices have finally come down for some of the cards. The average price of the cheaper cards is now around $130, a more fitting price given the card’s performance.

The timing for this leads into today’s launch. AMD is launching a new card, the Radeon HD 6790, at that same $150 price point. Based on the same Barts GPU that powers the Radeon HD 6800 series, this is AMD’s customary 3rd tier product that we’ve come to expect after the 4830 and 5830. As we’ll see NVIDIA had good reason to drop the price on the GTX 550 if they didn’t already, but at the same time AMD must still deal with the rest of the competition: NVIDIA’s GTX 460 lineup, and of course AMD itself. So just how well does the 6790 stack up in the crowded $150 price segment? Let’s find out.

  AMD Radeon HD 6870 AMD Radeon HD 6850 AMD Radeon HD 5830 AMD Radeon HD 6790 AMD Radeon HD 5770
Stream Processors 1120 960 1120 800 800
Texture Units 56 48 56 40 40
ROPs 32 32 16 16 16
Core Clock 900MHz 775MHz 800MHz 840MHz 850MHz
Memory Clock 1.05GHz (4.2GHz data rate) GDDR5 1GHz (4GHz data rate) GDDR5 1GHz (4GHz data rate) GDDR5 1050MHz (4.2GHz data rate) GDDR5 1.2GHz (4.8GHz data rate) GDDR5
Memory Bus Width 256-bit 256-bit 256-bit 256-bit 128-bit
VRAM 1GB 1GB 1GB 1GB 1GB
FP64 N/A N/A 1/5 N/A N/A
Transistor Count 1.7B 1.7B 2.15B 1.7B 956M
Manufacturing Process TSMC 40nm TSMC 40nm TSMC 40nm TSMC 40nm TSMC 40nm
Price Point ~$200 ~$160 N/A $149 ~$110

3rd tier products didn’t get a great reputation last year. AMD and NVIDIA both launched such products based on their high-end GPUs – Cypress and GF100 respectively – and the resulting Radeon HD 5830 and GeForce GTX 465 were eventually eclipsed by the GeForce GTX 460 that was cooler, quieter, and better performing at the same if not lower price. The problem with 3rd tier products is that they’re difficult to balance; 1st tier products are fully enabled parts that are the performance kings, and 2nd tier products are the budget minded parts that trade some performance for lower power consumption and all that follows.

While 2nd tier products are largely composed of salvaged GPUs that couldn’t make it as a 1st tier product, the lower power requirements and prices make the resulting video card a solid product. But where do 3rd tier products come from? It’s everything that couldn’t pass muster as a 2nd tier product – more damaged units functional units that won’t operate at lower voltages like a 2nd tier product. The GTX 465 and Radeon HD 5830 embodied this with power consumption of a 1st tier card and the performance of a last generation card, which made them difficult to recommend. This does not mean that a 3rd tier card can’t be good – the Radeon HD 4830 and GTX 260 C216 were fairly well received – but it’s a difficult hurdle to overcome.

Launching today is the Radeon HD 6790, the 3rd tier Barts part and like the rest of the Barts-based lineup, the direct descendent of its 5800 series counterpart, in this case the Radeon HD 5830. As is to be expected, the 6790 is further cut-down from the 6850, losing 2 SIMD units and half of its ROPs; mitigating this some are higher clockspeeds for both the core and the memory. With 800 SPs and 16 ROPs operating at 840MHz, on paper the 6790 looks a lot like a Radeon HD 5770 with a 256bit bus, albeit one that’s clocked slower given the 6790’s 1050MHz (4.2GHz data rate) memory clock.

From the 5830 we learned that losing the ROPs hurts far more than the SPs, and we’re expecting much of the same here; total pixel pushing power is halved, and MSAA performance also takes a dive in this situation. Overall the 6790 has 90% of the shading/texturing, 54% of the ROP capacity, half the L2 cache, and 105% of the memory bandwidth of the 6850. Or to compare it to the 5770, it has 98% of the shading/texturing capacity, 98% of the ROP capacity, and 175% of the memory bandwidth, not accounting for the architectural differences between Barts and Juniper.

Further extending the 5830 comparison, as with the 5830 AMD is leaving the design of the card in the hands of their partners. The card being sampled to the press is based on the 6870’s cooler and PCB, as the 6790’s 150W TDP is almost identical to the 151W TDP of the 6870, however like the 5830 no one will be shipping a card using this design. Instead all of AMD’s partners will be using their own in-house designs, so we’ll be seeing a variety of coolers and PCBs in use. Accordingly while we can still take a look at the performance of the card, our power, temperature, and noise data will not match any retail card – power consumption should be very close however.

At 150W AMD is skirting the requirement for 2 PCIe power sockets. Being based on a 6870 our sample uses 2 sockets and any other design using a 6870 PCB verbatim should be similar, but some cards will ship with only a single socket. This doesn’t impact the power requirements of the card – it’s roughly 150W either way – but it makes the card more compatible with lower-wattage PSUs that only come with 1 PCIe power plug.

As we mentioned previously, AMD is launching the 6790 at $150. With the GTX 550’s price drop its direct competitor is no longer the GTX 550, but rather the closest competitor is now cheap GTX 460 768MB cards, which on average are about the same $150. AMD’s internal competition is the 6850, which averages closer to $160. Technically the Radeon HD 5770 is also competition, but with it going for around $110 after rebate, it’s far more value priced than the 6790 is.

Meanwhile the 6790 name also marks the first time we’ve seen the 6700 series in the retail market. In the OEM market AMD has rebadged the 5700 series as the 6700 series, however that change won’t ever be coming to the retail market, making this the only 6700 series card we’ll see. It’s a bit odd to see one series shared by two GPUs so significantly different, but AMD bases this on the fact that the 5770/6770 and the 6790 are so close in terms of specs; they want to frame the 6790 in terms of the 5770/6770, rather than in terms of the 6800 series. If nothing else it’s a nice correction for the poor naming of the 6800 series; a 6830 would have been the 5830 but slower.

April 2011 Video Card MSRPs
NVIDIA Price AMD
  $700 Radeon HD 6990
$480  
$320 Radeon HD 6970
$240 Radeon HD 6950 1GB
  $200 Radeon HD 6870
$160 Radeon HD 6850
$150 Radeon HD 6790
$130  
 
$110 Radeon HD 5770

 



The Test

For the AMD lineup including the 6790, we’re using the Catalyst 11.4 preview driver. For NVIDIA’s lineup we’re using a mix of the release 265 and release 270 drivers – we’re using 270 for the GTX 550 and GTX 460 768MB, however if you’re familiar with the performance of these cards you’ll quickly notice that the performance in our test suite is identical to the release 265 drivers.

CPU: Intel Core i7-920 @ 3.33GHz
Motherboard: Asus Rampage II Extreme
Chipset Drivers: Intel 9.1.1.1015 (Intel)
Hard Disk: OCZ Summit (120GB)
Memory: Patriot Viper DDR3-1333 3 x 2GB (7-7-7-20)
Video Cards: AMD Radeon HD 6990
AMD Radeon HD 6970
AMD Radeon HD 6950 2GB
AMD Radeon HD 6870
AMD Radeon HD 6850
AMD Radeon HD 6790
AMD Radeon HD 5970
AMD Radeon HD 5870
AMD Radeon HD 5850
AMD Radeon HD 5830
AMD Radeon HD 5770
AMD Radeon HD 4870X2
AMD Radeon HD 4870
NVIDIA GeForce GTX 580
NVIDIA GeForce GTX 570
NVIDIA GeForce GTX 560 Ti
NVIDIA GeForce GTX 550 Ti
NVIDIA GeForce GTX 480
NVIDIA GeForce GTX 470
NVIDIA GeForce GTX 460 1GB
NVIDIA GeForce GTX 460 768MB
NVIDIA GeForce GTS 450
NVIDIA GeForce GTX 295
NVIDIA GeForce GTX 285
NVIDIA GeForce GTX 260 Core 216
Video Drivers: NVIDIA ForceWare 262.99
NVIDIA ForceWare 266.58
NVIDIA ForceWare 270.51 Beta
AMD Catalyst 10.10e
AMD Catalyst 11.1a Hotfix
AMD Catalyst 11.4 Preview
OS: Windows 7 Ultimate 64-bit


Crysis: Warhead

Kicking things off as always is Crysis: Warhead, still one of the toughest games in our benchmark suite. Even three years since the release of the original Crysis, “but can it run Crysis?” is still an important question, and for three years the answer was “no.” Dual-GPU halo cards can now play it at Enthusiast settings at high resolutions, but for everything else max settings are still beyond the grasp of a single card.

Unlike NVIDIA, AMD doesn’t advertise their cards around specific resolutions, however from Crysis it’s quickly apparent that the 6790 is better suited for 1680 than it is for 1920, particularly when anti-aliasing is involved.

Overall the 6790 is quite competitive with the 5830, the GTX 285, and the GTX 460 768MB here; 36.9fps at 1680 isn’t great, but it’s going to be playable. The problem for the 6790 is that the 6850 is 20% faster for around $10 more, and this is going to be a repeating scenario. If AMD dropped the price by $20 it would be a much better fit between the 6850 and 5770, and it would easily vanquish the GTX 550 Ti at that price.

The story with minimum framerates is much the same as it is with the averages. The 6790 actually manages to edge out the 5830 here, but the 6850 is still 20% ahead.



BattleForge

Up next is BattleForge, Electronic Arts’ free to play online RTS. As far as RTSes go this game can be quite demanding, and this is without the game’s DX11 features.

With BattleForge the situation for the 6790 improves some, and even with 4x MSAA it’s quite playable at 1920. 40fps+ would be a good showing against the GTX 550 Ti if the two were similarly priced at around $130, but at $150 the GTX 460 768MB is 10% ahead, and the 6850 is now 22% ahead. As it stands this is actually one of the worst showings for the 6790 versus the 6850, showcasing the fact that BattleForge is one of the more ROP-intensive games in our test suite.



Metro 2033

The next game on our list is 4A Games’  tunnel shooter, Metro 2033. Metro is quite a resource intensive game, and if Crysis is a tropical GPU killer, then Metro would be its underground counterpart.

From the perspective of the 6850, Metro 2033 is one of the best titles for the 6790; the 6850 is only 13% ahead at 1680, meanwhile the 6790 is also quite close to the GTX 460 768MB. Much of this has to do with the fact that we don’t use anti-aliasing on this game at 1680 due to just how resource intensive it is, so the ROP penalty is minimized here. However at the same time memory bandwidth isn’t doing the 6790 much good, and as a result it’s only 8% faster than a 5770. The 6790 once again does well versus the GTX 550, but we’ve long since established that at launch prices it’s not the 6790’s biggest threat.



HAWX

Ubisoft’s 2008 aerial action game is one of the less demanding games in our benchmark suite, particularly for the latest generation of cards. However it’s fairly unique in that it’s one of the few flying games of any kind that comes with a proper benchmark.

HAWX’s performance isn’t particularly tied to resolution, but it is tied to ROP capabilities. Here at 1920 it easily sails by with 70fps, and bumps that up to 78fps at 1680. All the while the 6850 is 30% ahead and even the GTX 550 Ti has an edge in performance. The difference may be a bit academic at these framerates, but this is still one of the worst games for the ROP-strapped 6790.



Civilization V

Civilization 5 is the latest incarnation in Firaxis Games’ series of turn-based strategy games. Civ 5 gives us an interesting look at things that not even RTSes can match, with a much weaker focus on shading in the game world, and a much greater focus on creating the geometry needed to bring such a world to life. In doing so it uses a slew of DirectX 11 technologies, including tessellation for said geometry and compute shaders for on-the-fly texture decompression.

Civilization V is another title that we don’t use MSAA on at 1680 due to the game’s already low performance and the additional strain of MSAA. This works to the advantage of the 6790, giving it some of the best results relative to the 6850 of our entire test suite. Here the two cards are in fact virtually tied, and Barts’ improved tessellator gives it 20% over the 5770. However NVIDIA’s continued strong showing here means that the 6850 is largely tagging out for the GTX 460 768MB here, which is why the GTX 460 is nearly 20% ahead, and even the GTX 550 isn’t too far behind. If more games were like Civilization V the 6790 would be in better shape, but the rest of the Barts lineup wouldn’t be doing nearly as well.



Battlefield: Bad Company 2

Now approaching a year old, Bad Company 2 remains as one of the cornerstone DX11 games in our benchmark suite. Based on the Frostbite 1.5 engine, it will be replaced in complexity by the DX10+ only Frostbite 2 engine (and Battlefield 3) later this year.  As BC2 doesn’t have a built-in benchmark or recording mode, here we take a FRAPS run of the jeep chase in the first act, which as an on-rails portion of the game provides very consistent results and a spectacle of explosions, trees, and more.

Bad Company 2 is the 3rd and final game we don’t use MSAA on for 1680. Here the 6790 can hit 77.3fps at that resolution, while it drops to a barely playable 41.1fps at 1920. Even without MSAA weighing the card down however, the 6850 still has 14% on it and the GTX 460 has 10%. It’s only against its underpowered competition that we see a victory, and even then while it’s 13% ahead of the GTX 550 it’s only 11% ahead of the 5770.



STALKER: Call of Pripyat

The third game in the STALKER series continues to build on GSC Game World’s X-Ray Engine by adding DX11 support, tessellation, and more. This also makes it another one of the highly demanding games in our benchmark suite.

At higher resolutions STALKER craves more memory than what 1GB cards can provide, but even at lower resolutions 768MB isn’t always enough. As a result the 6790 claims one if its only victories over the GTX 460 768MB by all of 3%. The 6850 is well ahead of the 6790 though by 17%, while the 6790 clears the 5770 by 10%.



DIRT 2

Codemasters’ 2009 off-road racing game continues its reign as the token racer in our benchmark suite. As the first DX11 racer, DiRT 2 makes pretty thorough use of the DX11’s tessellation abilities, not to mention still being the best looking racer we have ever seen.

DIRT 2 is another poor showing for the 6790. With NVIDIA’s normal performance advantage here the GTX 460 is well ahead, and even the GTX 550 Ti can edge out the 6790. Against AMD’s other cards the 6790 has 9% on the 5770, but the 6850 has 16% on the 6790. At nearly 50fps at 1920 the 6790 should be playable for most gamers at that resolution, but even the higher resolution doesn’t change the relative outcomes much.



Mass Effect 2

Electronic Arts’ space-faring RPG is our Unreal Engine 3 game. While it doesn’t have a built in benchmark, it does let us force anti-aliasing through driver control panels, giving us a better idea of UE3’s performance at higher quality settings. Since we can’t use a recording/benchmark in ME2, we use FRAPS to record a short run.

Mass Effect 2 is the most ROP sensitive game we have in our current test suite, making it the worst showing of the day for the 6790. The GTX 550 Ti wins by nearly 10%, the 6850 wins by 33%, and even the GTX 460 is ahead by 25%. The one bright spot is that at least the 6790 can beat the 5770, but once again it’s by less than 10%.



Wolfenstein

Finally among our benchmark suite we have Wolfenstein, the most recent game to be released using the id Software Tech 4 engine. All things considered it’s not a very graphically intensive game, but at this point it’s the most recent OpenGL title available. It’s more than likely the entire OpenGL landscape will be thrown upside-down once id releases Rage later this year.

Wolfenstein is easy enough to run that even the 6790 can just about hit 60fps at 1920. Even so its performance relative to other cards is quite poor. It’s 20% behind the 6850, and 13% behind the GTX 460 768MB. Even its showing against the Radeon HD 5770 is poorer than usual – it’s around 5% faster at either resolution.



Compute & Tessellation

Moving on from our look at gaming performance, we have our customary look at compute performance, bundled with a look at theoretical tessellation performance.

Our first compute benchmark comes from Civilization V, which uses DirectCompute to decompress textures on the fly. Civ V includes a sub-benchmark that exclusively tests the speed of their texture decompression algorithm by repeatedly decompressing the textures required for one of the game’s leader scenes.

Civilization V’s compute benchmark cares little for memory bandwidth or the architectural differences between Barts and Juniper; SPs and clockspeed are what matter here. As a result the 6790 narrowly averts a tie with the 5770 of all things, and the performance relative to NVIDIA’s cards isn’t any better.

Our second GPU compute benchmark is SmallLuxGPU, the GPU ray tracing branch of the open source LuxRender renderer. While it’s still in beta, SmallLuxGPU recently hit a milestone by implementing a complete ray tracing engine in OpenCL, allowing them to fully offload the process to the GPU. It’s this ray tracing engine we’re testing.

SmallLuxGPU ends up being one of the best showings for the 6790, as while it’s obviously compute bound, it definitely benefits from the architectural differences between Barts and Juniper. The 6790’s performance relative to the 6850 almost identically matches the theoretical performance difference, and in spite of the 5770 having a slight theoretical advantage of its own, the 6790 easily beats the 5770 by 16%. This opens up a small window for the 6790 as a lower-priced GPGPU product, but it’s a very small window – the program would need to excel on AMD cards and on Barts over Juniper. Otherwise we see SLG where the 6790 does well versus the 5770, but very poorly compared to NVIDIA’s cards.

At the other end of the spectrum from GPU computing performance is GPU tessellation performance, used exclusively for graphical purposes. Barts’ tessellation improvements should give it an edge over the 5770, but it still has to contend with the 6800 series.

At this point in time none of our games closely match our tessellation results, which shouldn’t be a surprise given the low usage of tessellation. Although Barts isn’t a tessellation monster it could do quite well in the future if tessellation takes off in a manner similar to how these benchmarks use it, but that’s a very big if.



Power, Temperature, & Noise

Last but not least as always is our look at the power consumption, temperatures, and acoustics of the Radeon HD 6790. Our power usage data should closely mirror any other 6790, but given the unique design of our card versus what AMD’s partners are going with, we can’t fully account for all the different designs.

On that note, at this point we do not know what the 6790’s default voltage is. None of our usual low-level tools recognize the 6790; it’s possible that AMD is using different controllers than on the 6800 series, or perhaps it’s related to drivers. In any case we believe it’s close to the 6870’s voltage of 1.17v, but we can’t measure it at this time.

Idle power consumption rarely changes among the different tiers of a GPU, so the fact that the 6790 pulls almost as much power at idle as the 6800 series should not come as a surprise. It does end up being worse than the GTX 550 Ti, but almost exactly alike the GTX 460.

Given AMD’s TDP numbers, we were expecting our power results to closely shadow our 6870 results. Instead we had a pleasant surprise: power consumption under Crysis is higher than the 6850, but not significantly so. In fact it’s still below the GTX 550 Ti even though it significantly outperforms said video card on this game, and even compared to the 5770 it’s not significantly worse for the 6790’s performance advantage. Not that it’s great to be consuming more power than a 6850 for less performance, but it could very well have been worse.

The situation under Furmark is even better surprisingly enough. The 6790 consumes less power than the 6850 here – not a ton less, but less. Perhaps more surprising is that compared to the 5770 it’s only consuming 3W more; this Barts chip may have a lot of functional units disabled, but that’s still quite remarkable, and is all the more proof of the optimizations AMD made for Barts compared to Cypress. This also makes it look exceptionally good versus the GTX 550 Ti and GTX 460 768MB, as it’s consuming 40-45W less.

With idle power consumption being identical to the 6800 series and using the same cooler, the idle temperature is similarly close.

Given the power numbers we saw earlier, the 6870’s cooler ends up being overkill for the 6790. As a result Crysis temperatures are quite low, although the fully exhausting cooler can’t keep up with the open cooler of the GTX 460. Then again our 5770 is an open cooler, and it’s still much warmer. Keep in mind that this is going to highly vary with the design of the cooler the partner uses though.

Temperatures under Furmark closely trend Crysis. An open cooler might be able to get the 6790 down to the low 70s.

Idle noise is identical to the 6800 series, as we’d expect.

Load noise is where the wheels begin to fall off on our 6790 sample. The card does so well with regards to power consumption and temperature, but noise is just as bad as the 6870. This undoubtedly is due to how AMD tweaked the 6790 engineering sample – which is to say it likely hasn’t been optimized much if at all since it won’t go into production. Given the power data we’ve seen the 6790 doesn’t need to be much louder than a 6850, so hopefully partner cards will reflect this. If not, the worst case scenario may very well be having all the noise of a 6870 and not nearly the performance.



Final Thoughts

Whether or not AMD calls the Radeon HD 6790 the successor of the Radeon HD 5830, that’s what it is. So 5830 comparisons are quite appropriate, both to look at what AMD did well at and where it doesn’t quite escapes its ancestor.

Perhaps the biggest problem with the 5830 was that it was a 3rd tier part from a high-end GPU; power, temperature, and noise could approach the levels of a high-end GPU without the matching performance. Barts is not a high-end GPU, and as such even if the 6790 were as hot/loud/power-hungry as the 6870, it wouldn’t be the end of the world. Thankfully it looks like power consumption is being kept in check, so partners should be able to develop reasonably cool & quiet cards. In practice the 6790 will probably be a bit worse than the 6850 in this regard, which again is not great given that it achieves only 85% of the performance, but it’s not unreasonable. The 6790 is still a 3rd tier product, but it’s learning from the past.

The problem with the 6790, much like the 5830 before it, is pricing. When you can pick up a GeForce GTX 460 768MB for $150 or a Radeon HD 6850 for $10 more, what sense does a $150 6790 make? It doesn’t make any sense, and there’s the problem. The impression I get is that AMD wanted to make a card to thoroughly trample the GTX 550 Ti, and indeed the 6790 can do that. The problem is that they’re pricing it against the GTX 460 and 6850 right now. The GTX 550 Ti is a good $20 lower (and probably should be cheaper still).

At the end of our 5830 review last year, we said the issue came down to $20: the 5830 was $20 too expensive for what it offered. It’s fitting then that this seems to be the same problem with the 6790. If it were a $130 card it would fit in well between AMD’s other cards; it would beat the GTX 550 Ti, and it would make NVIDIA think long and hard about what to do with the GTX 460 768MB. Instead AMD is committing the same mistake as the 5830 and as the GTX 550 Ti by launching it at $150. $150 is quickly becoming a great place to mislaunch cards.

Long term I’m a bit worried that the $150 price will stick, giving AMD a price floor to bring up 6800 series prices. The 6790 is solidly ahead of the GTX 550 Ti, so if that’s the only thing AMD bases all of their pricing around they can charge more than the GTX 550 Ti, and more for the 6800 series on top of that. I hope it doesn’t come to that, but we have seen video card prices creep up before.

For the time being there’s not much going for the 6790 to recommend it. Throw some rebates on the Radeon HD 6790 to get it down to $130 and we can talk. Until then the GeForce GTX 460 768MB or the Radeon HD 6850 are both much better products.

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