Sign in with
Sign up | Sign in
AMD Radeon HD 7870 And 7850 Review: Pitcairn Gets Benchmarked
By ,
1. Radeon HD 7870 and 7850: A Paper Launch by Any Other Name

If you follow the graphics industry, you probably already knew today’s AMD Radeon HD 7800-series launch was happening. The company told us to expect this back in December when it introduced Radeon HD 7970. It reminded us in January when the Radeon HD 7950 debuted, and again in February during the Radeon HD 7770 and 7750 briefings.

Consequently, we’re also not surprised that, as the Radeon HD 7870 and 7850 became public knowledge, supply of the Radeon HD 6970 and 6950 dried up. After all, it’s hard to recommend last generation’s card, still priced competitively, when it’s no longer for sale. The new models replace those older cards with similar suggested prices of $349 for the 7870 and $249 for the 7850.

Another Paper Preview Launch

Unfortunately, although we’re able to talk about the performance of Radeon HD 7870 and 7850, you won’t be able to buy the card until at least March 19th, AMD tells us. The company says that, because CeBIT and the Game Developers Conference fall so close to the official launch, it’d be difficult to keep information about the cards under wraps. Regardless of the explanation, it sucks to wait another two weeks for street pricing and a better feel for availability.

Cynicism aside, we’re still technology geeks at heart, and we’re desperately curious to know how the 7800-series cards measure up to the Radeon HD 6900s, which earned our affections in the past for their conservative power use, excellent CrossFire scaling, and rich display connectivity compared to Nvidia’s GPUs with two independent pipelines.

This is the third distinct Graphics Core Next-based ASIC from AMD in as many months. Code-named Pitcairn, we finally have a solution in between the flagship Tahiti and the entry-level Cape Verde. The graphics processor is composed of 2.8 billion transistors in a 212 mm2 die manufactured on TSMC’s 28 nm lithography node. That’s nearly twice as large as the GPU at the heart of Radeon HD 7770, but around two-thirds of Tahiti, which drives the Radeon HD 7970.

Pitcairn hosts 20 compute units, each with four vector units made up of 16 stream processors and a single texture unit. In an uncut GPU, those numbers multiply out to 1280 total shaders and 80 texture units. AMD shears off four compute units from Pitcairn to create the Radeon HD 7850, resulting in 1024 shaders 64 texture units.

The GPU’s back-end is made up of eight render partitions, each with four full-color ROPs, totaling 32 ROPs. Four 64-bit memory controllers yield an aggregate 256-bit memory bus. AMD doesn’t make any changes to this part of the chip; both the Radeon HD 7870 and 7850 sports identical back-ends.


Radeon HD 7870
Radeon HD 6970
Radeon HD 7850
Radeon HD 6950
Stream processors
12801536
1024
1408
Texture Units
80
966488
Full Color ROPs
32
3232
32
Graphics (Shdr) Clock
1000 MHz880 MHz860 MHz800 MHz
Texture Fillrate
80 Gtex/s
84.5 Gtex/s55 Gtex/s70.4 Gtex/s
Memory Clock
1200 MHz1375 MHz1200 MHz
1250 MHz
Memory Bus
256-bit256-bit256-bit
256-bit
Memory Bandwidth153.6 GB/s
160 GB/s153.6 GB/s160 GB/s
Graphics RAM
2 GB GDDR5
2 GB GDDR52 GB GDDR51-2 GB GDDR5
Die Size
212 mm2
389 mm2212 mm2389 mm2
Transistors (Billion)
2.8
2.642.82.64
Process Technology
28 nm40 nm
28 nm40 nm
Power Connectors
2 x 6-pin1 x 8-pin, 1 x 6-pin
1 x 6-pin2 x 6-pin
Maximum power (TDP)
175 W
250 W
130 W200 W
Price
$349 MSRP
$350-$410 (EOL)
$249 MSRP$250 (1 GB, EOL)
$270-$300 (2 GB, EOL)


In general, AMD’s Radeon HD 6900 family features more shaders and texture units, while the 7800s operate at higher clock rates. Remember also that both line-ups also employ different architectures optimized for different things. VLIW4 was the product of much evolution, and hence quite mature. Meanwhile, GCN is much newer. We’ve seen it completely tank in DirectX 9-class applications, and then deliver stellar performance in more modern titles.

All of the cards in the above chart feature 256-bit memory interfaces feeding 32 ROPs, but the 6900 series’ higher memory clock rates facilitate a little more bandwidth.

Interestingly, the Radeon HD 6950 only proffers about 10% fewer shaders than the Radeon HD 6970. In contrast, the Radeon HD 7850 comes armed with a roughly 25% deficit compared to Radeon HD 7870. AMD seems to have decided that it needed to spread its mid-range cards further apart from each other. I’ve often wondered if the Radeon HD 6950 cannibalized Radeon HD 6970 sales because they were so similar (surely it didn’t help that 6950s were getting updated via firmware to look even more like 6970s) That could be what AMD is trying to avoid this time around.

Although it’s tempting to look at raw specifications and draw comparisons, you really can’t, on account of the dissimilar architectures. We can, however, point out that all of AMD’s GCN-based cards put a special emphasis on maintaining exceptional performance at lower maximum power. The Radeon HD 7750 doesn’t even need a dedicated PCIe power connector, and yet its performance is often comparable to the Radeon HD 5770/6770. With maximum TDPs at 175 and 130 W, the Radeon HD 7870 and 7850 sport power ceilings that are 75 and 70 W lower than their predecessors, respectively. The Radeon HD 7870 requires two six-pin PCIe power connectors, and the Radeon HD 7850 only needs one. Lower power means less heat. Less heat translates to more conservative cooling. And that leaves the door open for gaming enthusiasts to enjoy quieter systems that go easier on the power bill. These cards might not even necessitate a power supply upgrade, if your machine is reasonably modern.

A Sizable Gap

We’re curious about the space between AMD’s $250 Radeon HD 7850 and its $160 Radeon HD 7770. Like it or not, the Radeon HD 6800s are gone for good. AMD isn’t taking orders on the 6870, 6850, or 6790. The company won’t comment on future products, but we find it hard to believe it’d abandon the $180-$230 market currently inhabited by the GeForce GTX 560, 560 Ti, and Radeon HD 6870. That leaves two likely possibilities for the future: a cheaper 1 GB version of the Radeon HD 7850, or perhaps a crippled version of the 7850 that might populate a lower position in the hierarchy.

Radeon HD 7870 and 7850

Officially, AMD gives its Radeon HD 7870 the same GHz Edition suffix as the Radeon HD 7770, indicating only that the core breaks the completely arbitrary gigahertz barrier.

As far as appearances go, the Radeon HD 7870 is quite similar to the Radeon HD 6870. It’s 9.5” long with two six-pin auxiliary power inputs. The biggest functional difference between old and new is the loss of a DVI display connector. As with the flagship Radeon HD 7970, AMD says it got rid of the second DVI output to improve exhaust airflow. Two mini-DisplayPort connectors and a single HDMI port remain intact. Of course, the card’s style is a little different, adhering to the tapered end we’ve seen from other 7000-series models.

Keep in mind that the Radeon HD 7870 actually replaces the 6970, though, and not the 6870. The higher-end 6970 is an inch longer, and it requires eight- and six-pin power inputs to feed an additional 75 W.

We like the 7870’s more compact dimensions, but enthusiasts will be disappointed to learn about two notable omissions: a BIOS selector switch and dual CrossFire connectors. Unlike the Radeon HD 6900s, which scaled up to four cards in a CrossFire array, the Radeon HD 7870 and 7850 can only be used in pairs. Moreover, the lack of a backup firmware makes flashing the BIOS riskier.

The reference Radeon HD 7850 seems identical to the 7870 with one exception: a single six-pin power input (rather than two), reflecting the 7850’s lower 130 W typical board power rating.

But the reference card isn’t necessarily representative of what you’ll see at retail, and some of the models AMD showed us are actually quite a bit smaller. 

Almost all of the partner boards share the same combination of one DVI-D output, a single HDMI connector, and twin mini-DisplayPorts. Based on the pictures AMD provided, the lone exception is XFX’s model with two DVI-D outputs.

2. Features, MLAA 2.0, And SSAA Updates

The Radeon HD 7800 family includes the same list of features inherent to the other 7000-series cards. It centers on the Graphics Core Next architecture, it offers an evolved implementation of Eyefinity, it supports the same general-purpose GPU compute features as the other cards, it boasts ZeroCore Power management, and its tessellation performance is improved. Then, there are all of the capabilities that AMD claims, but that we can’t test: discrete digital multi-point audio (DDMA), Partially Resident Textures (PRTs), 3 GHz Fast HDMI support, and DirectX 11.1/OpenCL 1.2/DirectCompute 11.1 support. We covered all of that in our Radeon HD 7970 preview, so feel free to read that piece for more background.

We’re still missing one touted Radeon HD 7000 series feature, though: the video codec engine, or VCE. This is a multi-stream hardware-based H.264 encoder that potentially represents AMD’s answer to Intel’s Quick Sync technology. What we’ve been told, however, is that software for the feature currently exists, but because the drivers aren’t ready, it’s toggled off. At some point in the future when AMD is ready to go, it’ll switch VCE on and whatever application infrastructure is in place will work. Company representatives tell us to expect functionality in about a month.

Morphological Anti-Aliasing 2.0

This feature has nothing to do with the Radeon HD 7000 series specifically, as it’s an update to the morphological filtering algorithm used by all of AMD’s cards, from the Radeon HD 4000s onward. The company is claiming enhanced image quality and better performance with its improved MLAA 2.0 that’ll be included with the Catalyst 12.3 beta and Catalyst 12.4 WHQL drivers.

Since we have access to a preview version of 12.3, we ran a few tests to see how AMD’s updated software affects performance, if it can keep pace with Nvidia’s fast FXAA software-based anti-aliasing, and if image quality is better.

We used The Elder Scrolls V: Skyrim for our MLAA 2.0 tests because it’s a game that suffers from a lot of foliage aliasing artifacts that aren’t corrected by hardware-based multisample anti-aliasing. It’s also a good opportunity to compare MLAA 2.0 to FXAA, as the game includes native support for Nvidia’s technology.

It turns out that some games are buggy with MLAA and Skyrim seems to be one of them, making it a less than ideal platform for drawing comparisons between AMD’s first- and second-generation implementations. Fortunately, we can at least conclude that whatever issues were present previously are fixed. Overall performance falls short of Nvidia’s FXAA, but frame rates are only part of the story. Graphics quality is at least as important.

As you can see, FXAA yields a blurrier picture than AMD’s morphological anti-aliasing, and MLAA 2.0 results in an even crisper picture compared to the original. This might be something we revisit in a future story. For now, due to yet another tight deadline, we’re forced to move on.

Supersampling Anti-Aliasing Improvements

AMD claims that the Catalyst 12.2 driver adds supersampling support for DirectX 10 and 11 games, the lack of which we lamented in last year’s Anti-Aliasing Analysis, Part 1: Settings And Surprises article. Although supersampling is often unusable due to a large performance hit, it’s tied to AMD’s Adaptive Anti-aliasing, a largely ignored mode that has tremendous potential for improving image quality in games with aliased transparent textures without the huge performance penalty of SSAA. As we mentioned in that article, Nvidia’s implementation (called Transparent AA) enjoyed much better game compatibility with new titles. So we’re excited about the prospect of a reliable Adaptive AA mode, too.

AMD also says that automatic level-of-detail adjustments will be included with the Catalyst 12.3 and 12.4 WHQL drivers to improve the sharpness of textures while using SSAA. We’ve been told that this feature “is currently only available on Southern Islands-based cards." This isn’t something we were able to find proof of in the limited tests we had time to perform, but we plan to dig deeper into anti-aliasing in a follow-up article.

3. Texture Optimizations And The Radeon HD 7000s

As we go through the benchmarks, you’ll see that the Radeon HD 7800s do an incredibly good job of applying Adaptive anti-aliasing to our Skyrim benchmark sequence. The numbers were so impressive, in fact, that we went out of our way to snap screenshots in order to validate the resulting image quality, too. As it turns out, they do; Adaptive AA on the 7800s looks similar to the Radeon HD 6900s, putting our minds at ease.

While we were scrutinizing those Adaptive AA results, however, we couldn’t help but notice that some textures appeared noticeably blurrier in the Radeon HD 7800 screenshots. We first assumed a setting had changed in the game or driver. But double-checking proved that wasn’t the case. Further investigation showed that the Radeon HD 7800-series cards match the Radeon HD 6900’s crisper output if the Catalyst A.I. texture filtering quality slider is moved from its default (Quality) to the highest (High Quality) setting.

So, to be clear, using the exact same 8.95.5 driver at its default settings, the Radeon HD 7800s deliver blurrier textures than the Radeon HD 6900s. Take a look:

The differences are not colossal, and you probably wouldn’t notice them during game play (we didn’t). But they're easily identifiable in screen shots. We don’t want to overstate the impact of what we’re seeing. But, on the other hand, we take reductions in image quality seriously because the slope is slippery, and we’ve seen this before.

This issue came up very late in our testing. We asked AMD for comment, but don’t have an official response as of yet. Moreover, questions remain: Are the Radeon HD 7800 cards enjoying higher performance as a result of an optimization? Could this be an unintentional bug? How much better would the Radeon HD 6900s look if we also bumped their Catalyst A.I. slider up to High Quality? We absolutely plan to answer all of those questions after we collect more data. And we’ll update the story once we get some more feedback from AMD.

4. Test Setup And Benchmarks

Today’s story is going to be a little different than what you’ve seen from us in the past. The Radeon HD 7850 that AMD sent our US office was so unreliable that it wasn’t usable in a vast number of benchmarks. More on that when we break into the individual tests. AMD wasn’t able to get us a working replacement, so much of our performance data comes from Tom’s Hardware DE by way of Igor Wallosek. The result is that we have two different test systems.


Tom's Hardware DE
Tom's Hardware US
CPU

Intel Core i7-2600K (Sandy Bridge),
@ 4.5 GHz, Hyper-Threading enabled

Intel Core i7-3960X (Sandy Bridge-E),
@ 3.6 GHz, Hyper-Threading enabled
Motherboard

Gigabyte Z68X-UD7 B3
Socket 1155, Chipset: Intel Z68

ASRock X79 Extreme9
LGA 2011, Chipset: Intel X79
Networking
On-Board Gigabit LAN controllerOn-Board Gigabit LAN controller
Memory

Kingston HyperX,
2 x 4 GB, 1600 MT/s

Corsair Vengeance LP PC3-16000,
4 x 4 GB, 1600 MT/s, CL 8-8-8-24-2T
Graphics

AMD Radeon HD 6950
800 MHz GPU, 1 GB GDDR5 at 1250 MHz

AMD Radeon HD 6970
880 MHz GPU, 2 GB GDDR5 at 1375 MHz

AMD Radeon HD 7850
860 MHz GPU, 2 GB GDDR5 at 1200 MHz

AMD Radeon HD 7870
1000 MHz GPU, 2 GB GDDR5 at 1200 MHz

AMD Radeon HD 7950
800 MHz GPU, 3 GB GDDR5 at 1250 MHz

Nvidia GeForce GTX 560 Ti
822 MHz GPU, 1 GB GDDR5 at 1002 MHz

Nvidia GeForce GTX 570
732 MHz GPU, 1.25 GB GDDR5 at 950 MHz

Nvidia GeForce GTX 580
772 MHz GPU, 1.5 GB GDDR5 at 1002 MHz

Hard Drive

Kingston V100+ 256 GB (SSD)

Samsung 256 GB (SSD)

Power

ePower EP-1200E10-T2 1200 W
ATX12V, EPS12V

ePower EP-1200E10-T2 1200 W
ATX12V, EPS12V
Software and Drivers
Operating System
Microsoft Windows 7 x6, Service Pack 1
DirectX
DirectX 11
Graphics Drivers
AMD Catalyst 12.3 beta
5. Benchmark Results: 3DMark 11 And Unigine Heaven

3DMark suggests that the Radeon HD 7870 approaches GeForce GTX 580-class performance, while the Radeon HD 7850 is in the same league as AMD’s Radeon HD 6970 and Nvidia’s GeForce GTX 570. If those observations carried through all of our tests, we’d be delighted. A $350 Radeon HD 7870 would effectively undercut its competition by $100.

The Radeon HD 7850 would also be attractive at $250, about $80 less than a Radeon HD 6970 or GeForce GTX 570. Of course, we won’t know where street prices fall until AMD makes these cards available, purportedly in a couple of weeks.

The results in Unigine are similar to 3DMark 11.

6. Benchmark Results: Battlefield 3

Our first actual game benchmark is Battlefield 3, the graphically impressive shooter from Swedish developer Digital Illusions CE. Does the Radeon HD 7800 series perform as well in a real game as it did in our synthetics?

AMD’s Radeon HD 7870 serves up impressive results that end up close to Nvidia’s GeForce GTX 580 and its own Radeon HD 7950. Unfortunately, the Radeon HD 7850 falls short of our expectations until we hit the highest resolution and detail settings.

7. Benchmark Results: Metro 2033

Although Metro 2033 is an older title, it remains one of the most demanding benchmarks in our suite.

The Radeon HD 7870 continues to impress with performance that approaches AMD’s Radeon HD 7950. The Radeon HD 7850 also fares fairly well, considering its suggested retail price.

8. Benchmark Results: Aliens Vs. Predator

Aliens Vs. Predator is another DirectX 11-based benchmark with features like tessellation and HDAO:

The Radeon HD 7800s deliver predictable performance.

However, Radeon HD 6970 raises eyebrows by besting the GeForce GTX 580 and approaching AMD’s Radeon HD 7950.

9. Benchmark Results: Crysis 2

Crysis 2 launched as a DirectX 9 game, but DirectX 11 support was added later through a patch. We like to run both code paths to compare performance.

Interestingly, we’ve seen great frame rates from the Radeon HD 7000-series cards using DirectX 11. Conversely, the new architecture seems to absolutely tank faced with DirectX 9.

AMD’s Catalyst 12.3 beta driver seems to fix the performance problems in Crysis 2 with DirectX 9. The new cards demonstrate much better frame rates.

Nvidia’s GeForce cards generally outperform competing AMD boards, but the finishing order is tight.

10. Benchmark Results: Mafia 2

AMD’s Radeon HD 7800-series cards seem to perform better as the resolution and detail levels increase. This is particularly true for the Radeon HD 7850. 

11. Benchmark Results: GTA IV

Grand Theft Auto IV used to be a regular staple in our benchmark suite. A lot of folks still enjoy seeing it, though this console port scales pretty terribly.

As expected, then, the game runs fairly squarely into a wall at 1920x1080. Increasing the resolution to 2560x1440 helps put a little distance between the various contenders, and we see the Radeon HD 6950 1 GB outperform the 2 GB Radeon HD 7850.

12. Benchmark Results: Batman: Arkham Asylum

While this game’s DirectX 11 code path was very buggy when it launched, a patch recently fixed the most egregious problems.

Despite fairly predictable performance numbers at 1920x1080, selecting extreme detail settings and a 2560x1440 resolution destroys the 7800 series’ results. The significance of that outcome is minimal, though, since none of our contenders yield playable frame rates. 

13. Benchmark Results: DiRT 3

At 1920x1080, the Radeon HD 7870 outperforms the 7950, strangely enough. Even at 2560x1440 the two cards finish very close together.

Meanwhile, the Radeon HD 7850 is just barely beaten by the older 6970 at 1920x1080. Push resolution to 2560x1440, though, and the Radeon HD 7850 drops to the point where even a GeForce GTX 560 Ti beats it. Clearly, something is very wrong there.

14. Benchmark Results: StarCraft II

Our StarCraft II benchmark results require a little background. This was one of the games tested in our German lab. Unfortunately, the Radeon HD 7850 they received wasn’t stable either. So, Igor dialed his core clock back to 845 MHz in order to make it through this test.

Incidentally, World of Warcraft (another Blizzard title) was the US lab’s most problematic game to benchmark.

The most surprising results in StarCraft II come from our Radeon HD 7850. Although we were able to complete benchmarks successfully with the underclocked card, there’s still something very wrong with where it places.  

15. Benchmark Results: The Elder Scrolls V: Skyrim

Bethesda’s incredibly popular The Elder Scrolls V: Skyrim recently received a significant patch that put more of an emphasis on graphics performance. Let’s begin with 8x MSAA in conjunction with FXAA to smooth out the edges of foliage:

The new 7800-series boards do well in this game, both outrunning AMD’s Radeon HD 6970.

This is one of those titles where AMD’s Adaptive AA feature really interested us. Because there are so many transparent textures on leaves, branches, and plants, applying Adaptive AA could make a profound impact on graphics quality.

We’re also able to test Nvidia’s Transparent AA technology, which similarly anti-aliases transparent textures.

With Adaptive AA enabled, AMD’s Radeon HD 7800-series cards compare much more favorably to the Radeon HD 6900-series boards. In fact, both 7800s blow right past the fastest card in our charts, Nvidia’s GeForce GTX 580.

To be fair, Nvidia’s TrSSAA looks a little better than AMD’s Adaptive AA in this game. Notice also that the Radeon HD 7800s are faster when Adaptive AA is turned on compared to MSAA with FXAA in the charts up top. Strange though that may be, we confirmed it through multiple iterations of our benchmark. We also took screen shots that prove the 7800’s Adaptive AA yields the same output quality as the 6900s, despite the performance difference.

16. Benchmark Results: World Of Warcraft

The Radeon HD 7800s don’t do particularly well in World of Warcraft, finishing behind their respective predecessors, albeit just slightly. More importantly, they succumb to the comparable GeForce cards they’ve been matching pace with up until now.

The finishing order is the same with 8x AA applied. With that in mind, all of the Radeon cards average more than 60 frames per second at both resolutions, yielding playable performance.

Finally, we have to mention that the Radeon HD 7850 crashed over and over during testing, requiring far too many reboots before we were finally able to capture useable benchmark results.

17. Benchmark Results: Sandra 2012

Let’s move on to compute performance. Sandra 2012 provides some convenient OpenCL benchmarks for us to compare, so let’s start with general purpose processing:

The Radeon HD 7800 series’ floating point performance is exceptional, though double-precision throughput is significantly lower than the 6900 series.

The new Radeons enjoy less memory bandwidth (called internal bandwidth by Sandra) than the 6900s.

However, PCI Express 3.0 compatibility facilitates significantly more throughput between our 7800-series cards and our Sandy Bridge-E-based test bed compared to the PCIe 2.0-capable 6900s. 

18. Benchmark Results: MediaEspresso, Luxmark 2.0, Bitmining

If these numbers seem vaguely familiar, it’s because we saw them once before in our Radeon HD 7700 series launch. After emailing back and forth with the helpful folks at CyberLink, we established that, at some point, AMD had pulled a couple of DLLs from its drivers, preventing MediaEspresso from utilizing hardware-accelerated encoding.

Now we see that support for accelerated encoding is available again. However, performance does not change.

It’s insane that we were able to test this feature and demonstrate its benefit more than a year ago when Intel’s second-gen Core processor first launched (Intel’s Second-Gen Core CPUs: The Sandy Bridge Review), and it’s now completely broken in multiple successive driver builds for some reason.

We use LuxMark to help evaluate the compute potential of AMD’s Radeon HD 7000-series cards, and our findings with the 7800s confirms GCN’s strengths in this discipline. The Radeon HD 7850 is the fourth-fastest card in AMD’s new line-up and it beats the Radeon HD 6970, last year’s top-of-the-line single-GPU flagship.

AMD’s Radeon cards are the favorites for Bitcoin miners. Although the 7800s continue outpacing anything from Nvidia, they don’t overtake the 6900-series cards. It’s probable that the client’s implementation of OpenCL differs from LuxMark’s.

19. Power Consumption

The Radeon HD 7900- and 7700-series cards have already shown us the 28 nm manufacturing node’s implications for power. AMD claims its 7800s are similarly efficient.

At idle, sitting on the Windows 7 desktop, both 7800s deliver the lowest system power results of the cards we tested.

In addition to their low active idle power, the 7000-series Radeons benefit from a suite of features collectively referred to as ZeroCore. When a display connected to one of these cards drops into standby mode, the card is able to spin down and shed another 10 W or so of power consumption. Compare the Radeon HD 7800s to Nvidia’s GeForce GTX 580, which drops a single watt, and still consumes more than 40 W as our test PC sits idle. 

AMD’s Radeon HD 7870 uses significantly less power than Nvidia’s GeForce GTX 580, while achieving similar results. That comparison typifies what we’ve seen from some of the other 7000-series boards: competitive performance at markedly lower power.

20. Temperature And Noise

Before we discuss the following results, we need to point out that a lot of the cards in our lab come from board partners. They’re not reference designs, and so their thermal and acoustic performance will differ from the AMD’s samples. This gives them a potential advantage, depending on the vendor’s priorities. In an effort to maintain transparency, when a card isn’t a reference design, we label it as such, making sure clock rates match the reference specification.

Despite competing custom coolers, the Radeon boards demonstrate low idle temperatures. This is likely a consequence of low power use translating to modest thermal output.

Load temperatures are also conservative—impressive given the large aftermarket heat sinks with which these reference designs compete.

None of these cards make much noise at idle, but we’re more concerned with their behavior under a 3D load.

Modest thermals turn into great acoustics for both of the Radeon HD 7800s. We just wish the Radeon HD 7970 was as quiet as these two mid-range boards.

21. Radeon HD 7800s: Great Performance, Price, And Power. But Are They Ready?

Before we go any further, consider the aggregate average game performance at 1920x1080:

The Radeon HD 7870 and 7850 offer impressive performance, extremely low power usage, and attractive estimated prices (at least in North America; we're sorry, Europeans) compared to cards offering similar performance. They run coolly and quietly, making them easy to live with, too. That covers the most important questions gamers ask when they hear about new graphics cards. From almost every angle, consider us impressed. Sure, we could complain yet again about the lack of VCE support several months after AMD announce the feature, but that doesn’t affect these cards’ ability to play games.

Unfortunately, our in-depth evaluations in two different labs at opposite ends of the world turned up a handful of unexpected issues, too. Igor Wallsosek in our German office reports back with a lot of Radeon HD 7850-related issues: NewTek’s LightWave crashes with 4x AA or higher, Autodesk’s 3ds Max crashes in DirectX mode, and the card is incapable of running StarCraft II at its stock clocks. It would be tempting to chalk all of that up to a bad sample, but we had problems with our 7850 as well. World of Warcraft was particularly unstable, requiring a restart after every crash. And sometimes our test bed simply wouldn’t boot with the 7850 installed. Then there’s the whole issue of texture quality issues on both of the new 7800s. Oof.

We’ve never seen a graphics card with so much potential for $250. But there are clearly issues to work out of the Radeon HD 7850. In this case, a paper launch might be the best possible thing for AMD, especially if it needs to tweak hardware specs and the driver. Interestingly, AMD claims that none of its partners plan to use the reference board design. If our problems are specific to AMD’s implementation, shipping 7850s could be better behaved. With weeks to go before these cards are available, we’re able to reserve judgement. On the other hand, both of the Radeon HD 7870s in our labs work great, so there’s little stopping us from recommending that card. Priced at $350, it performs a lot like the $470-ish GeForce GTX 580 and the $465 Radeon HD 7950. At this point, it’s hard to see spending extra money on either of those two technically higher-end boards unless you need a firmware selector switch (which the 7950 offers) or a three-/four-way multi-card setup. We can’t issue the Radeon HD 7870 an award, since it’s not available for sale, but consider us impressed. 

There’s just one little caveat. We already know that Nvidia’s next-gen architecture is very near on the horizon. We already have to wait for the Radeon HD 7800s to hit store shelves. Could it be so bad to wait a little while longer to see how Kepler does? As a rule, I feel that waiting for “the next big thing” is a fool’s game when it comes to technology. But with two new architectures on the cusp of going head-to-head, weeks apart, this could an exception to that personal policy.

Update: We’ve been working to diagnose the source of our stability issues with the Radeon HD 7850 card provided to us by AMD. Additionally, the company sent us a second card for testing.

Our efforts reveal compatibility issues with our original Core i7-3000-series test platform. A second configuration, built using a Gigabyte X58A-UD3R motherboard and Core i7-920 CPU, is much more stable with the Radeon HD 7850 installed. In fact, we’re able to overclock both samples in excess of 1 GHz, although we still experience crashes at in World of Warcraft with 4x MSAA at stock clocks. Given additional testing, we’re also seeing instability with the 7870 in WoW with anti-aliasing applied. We have to suspect that there’s a game or driver issue at fault.

To recap, both Radeon HD 7850s are unstable on our Sandy Bridge E-based configuration. Sometimes it takes multiple attempts to boot up. Other times we encounter texturing anomalies. This is puzzling because no other graphics cards demonstrate stability problems on this platform, including the Radeon HD 7870 sample based on an identical reference PCB.

As for our Tom’s Hardware lab in Germany, the sample there suffers intolerance to overclocking on multiple test beds, and needs to be underclocked slightly in order to complete a StarCraft II benchmark. This card also demonstrates instability when using professional workstation apps in OpenGL mode: Lightwave crashes when 4x MSAA is applied, and Maya is generally unreliable under OpenGL.

With this new information in hand, we’re inclined to believe the Radeon HD 7850 problems in the Tom’s Hardware US lab are primarily related to platform compatibility, whereas the Tom’s Hardware DE lab received a problematic sample. Based on this, we’re hopeful that the Radeon HD 7850s that ship to retail won’t exhibit the issues experienced by either Tom’s Hardware office. We’re looking forward to testing its overclocking capabilities in a future piece.