AMD Radeon HD 8790M: Next-Gen Mobile Mainstream Graphics Preview
Table of contents
AMD sent over some of its lab gear: an interposer
card and two PCI Express-based boards with MXM modules...one of which
hosted its upcoming Radeon HD 8790M GPU. At long last, the GCN
architecture is hitting mainstream notebooks in its 28 nm glory.
Here we were just saying not to expect AMD Radeon HD 8000-series graphics cards until later in 2013 in Best Graphics Cards For The Money: December 2012, and the company sends over its Radeon HD 8790M. Cool, right? We haven't even reviewed a desktop-based 8000-series card yet.
Well, not so fast. AMD does currently offer mobile graphics processors based on its Graphics Core Next architecture. However, those are limited to the high-end of its Radeon HD 7700, 7800, and 7900 families. Everything in the 7600-series and lower centers on the company's VLIW5 shader configuration, which you last saw make news on the desktop when it launched the Radeon HD 6800 series in October of 2010. So, yeah. It's high time that AMD starts nudging the far superior GCN architecture and 28 nm manufacturing into mainstream and entry-level mobile designs.
Enter the Radeon HD 8000M-series chips.
What's up with the name, then? Call it carry-over inflation from the Radeon HD 7000M line-up, which also mixed multiple architectures. The take-away, right up front, is that even though we're previewing a Radeon HD 8790M, this isn't the 8000-series you're expecting on the desktop. Rather, it's AMD's effort to get GCN into the mobile space, an exciting-enough prospect in its own right, given that small, lightweight notebooks stand to gain quite a bit from an energy-efficient design able to bolster performance significantly.
We're not particularly happy about the model confusion, as we've pointed out many times in the past. But AMD didn't leave itself much room to roll out GCN-enabled Radeon HD 7000M-series parts. And besides, Windows 8 is here. OEMs want to see shiny new names to go along with their latest models.
Those marketing shenanigans don't diminish AMD's claim that the Radeon HD 8000Ms are going to be quite a bit faster than the VLIW5-based GPUs they replace. On the desktop, we saw the Radeon HD 7000-series add-in cards not only improve performance appreciably, but the GCN architecture also helped ratchet up efficiency and improve the company's standing in more general-purpose compute workloads. Equally impressive were the speed-ups AMD's driver team managed to coax from GCN after the architecture's introduction. We expect that GCN-enabled mobile parts to wield the same benefits, plus enjoy a more mature driver (including a fixed implementation of its switchable Enduro technology, which was recently patched to address a frame rate-limiting bug).
As you can see, the Radeon HD 8000Ms actually slot in underneath AMD's Radeon HD 7800M-series in the Q1 product line-up. AMD plans to fix this in Q2, when 7800M- and 7900M-series replacements get the entire portfolio into the Radeon HD 8000M family.
If you've heard rumors about the Venus and Mars parts, and thought they had something to do with the desktop, then you'll be surprised to learn that those are the code names for two mobile GPUs. Venus is one component, while Mars is divided into three families, all equipped with 384 Stream processors, but operating at different clock rates.
AMD does plan to turn features on and off to differentiate its new GPUs, too. For example, the Mars-based Radeon HD 8790M we're previewing does not include support for the company's Video Codec Engine (VCE). Conversely, the Radeon HD 8800Ms, armed with Venus, are expected to include VCE functionality to speed up video encoding and decoding in hardware.
You'd think that would make it hard to benchmark the Radeon HD 8790M. However, we have a bit of hardware in the lab that should allow us to draw a comparison between AMD's next-generation mobile line-up and the one it replaces. The interposer card in the image below drops into a PCI Express x16 slot, and accommodates an MXM module. AMD and Nvidia use these things in their own labs during the bring-up process. They make it possible to do all of the testing needed before an OEM integrates a GPU into its own notebook design.
The interposer solves some problems, even as it introduces others. Let's start with its advantages.
First, and perhaps most important for the scientifically-minded out there, it allows us to maintain a common test platform. Were we to instead benchmark notebooks from competing vendors against each other, we'd have to take different processors, thermal limits, clock rates, memory capacities, and motherboards into consideration. This way, the only things changing are the MXM modules. Moreover, getting our hands on these components allows us to test weeks or months before OEM notebooks start shipping.
Conversely, we're painfully aware that dropping mobile hardware into a desktop environment ignores many of the constraints OEMs face when it comes to integration. We don't get a sense for thermal output or battery consumption during a 3D workload. That makes it easy to create an unrepresentative comparison. See the heat sink on the 8790M? It's quite a bit larger than the 7670M's cooling solution. Could we be facing a match up that never pans out in the real-world? Perhaps, though a 28 nm processor and proven-better efficiency give the GCN-based part headroom that the prior-gen part doesn't enjoy. When we first started this evaluation, AMD told us we were working with a Radeon HD 8770M, and that it was as close to a drop-in replacement for the 7670M as you'd find, matching its TDP. But after GPU-Z indicated that we were dealing with a Radeon HD 8790M, the company corrected itself and confirmed the higher-end part, operating at 850 MHz with a 900 MHz boost state available.
There's no way for us to be certain that the previous-gen part, the part we originally thought we'd be testing, and the 8790M we actually have in the lab would all work in the same notebook, or if their respective thermal and power attributes would preclude one or more from sharing compatibility. So, we're hedging our bets by not involving Nvidia in this discussion, and recommending that you consider the performance we're presenting as a comparison between two distinct models in AMD's line-up, which you wouldn't necessarily find in the same chassis.
The specs on the Radeon HD 7670M match what we are expecting. GPU-Z doesn't fully recognize the 8790M, but it does pick up its maximum 900 MHz boost clock.
Again, because the new Radeon HD 8000M-series GPUs aren't yet
shipping in notebooks, we're using a desktop-oriented setup with a PCI
Express interposer to preview the performance of AMD's GCN-enabled
mainstream mobile graphics processors. Although we could have used an
overclocked Core i7-3770K to crush the potential of a platform-oriented
bottleneck, we stepped down to a Core i5-2500K instead. Though still
fast, this part running at its stock settings is perhaps a better match
to the performance of what you might find in a notebook (even if its 95 W
TDP is way out of bounds).
Here we were just saying not to expect AMD Radeon HD 8000-series graphics cards until later in 2013 in Best Graphics Cards For The Money: December 2012, and the company sends over its Radeon HD 8790M. Cool, right? We haven't even reviewed a desktop-based 8000-series card yet.
Well, not so fast. AMD does currently offer mobile graphics processors based on its Graphics Core Next architecture. However, those are limited to the high-end of its Radeon HD 7700, 7800, and 7900 families. Everything in the 7600-series and lower centers on the company's VLIW5 shader configuration, which you last saw make news on the desktop when it launched the Radeon HD 6800 series in October of 2010. So, yeah. It's high time that AMD starts nudging the far superior GCN architecture and 28 nm manufacturing into mainstream and entry-level mobile designs.
Enter the Radeon HD 8000M-series chips.
What's up with the name, then? Call it carry-over inflation from the Radeon HD 7000M line-up, which also mixed multiple architectures. The take-away, right up front, is that even though we're previewing a Radeon HD 8790M, this isn't the 8000-series you're expecting on the desktop. Rather, it's AMD's effort to get GCN into the mobile space, an exciting-enough prospect in its own right, given that small, lightweight notebooks stand to gain quite a bit from an energy-efficient design able to bolster performance significantly.
We're not particularly happy about the model confusion, as we've pointed out many times in the past. But AMD didn't leave itself much room to roll out GCN-enabled Radeon HD 7000M-series parts. And besides, Windows 8 is here. OEMs want to see shiny new names to go along with their latest models.
Those marketing shenanigans don't diminish AMD's claim that the Radeon HD 8000Ms are going to be quite a bit faster than the VLIW5-based GPUs they replace. On the desktop, we saw the Radeon HD 7000-series add-in cards not only improve performance appreciably, but the GCN architecture also helped ratchet up efficiency and improve the company's standing in more general-purpose compute workloads. Equally impressive were the speed-ups AMD's driver team managed to coax from GCN after the architecture's introduction. We expect that GCN-enabled mobile parts to wield the same benefits, plus enjoy a more mature driver (including a fixed implementation of its switchable Enduro technology, which was recently patched to address a frame rate-limiting bug).
AMD's Mainstream Radeon HD 8000M-Series
| AMD Notebook Graphics Line-Up In Q1'13 | ||||||
|---|---|---|---|---|---|---|
| Radeon HD 8500M | Radeon HD 8600M | Radeon HD 8700M | Radeon HD 8800M | Radeon HD 7800M | Radeon HD 7900M | |
| Stream Processors | 384 | 384 | 384 | 640 | 640 | 1280 |
| Engine Clock | Up to 650 MHz | Up to 775 MHz | Up to 850 MHz | Up to 700 MHz | Up to 800 MHz | 850 MHz |
| Memory Clock | Up to 1125 MHz (GDDR) Up to 1000 MHz (DDR3) | Up to 1125 MHz (GDDR) Up to 1000 MHz (DDR3) | Up to 1125 MHz (GDDR) Up to 1000 MHz (DDR3) | Up to 1125 MHz (GDDR) | Up to 1000 MHz (GDDR5) | 1000 MHz (GDDR5) |
| Single-Precision Compute | 537 GFLOPS | 633 GFLOPS | Up to 691 GFLOPS | Up to 992 GFLOPS | Up to 1024 GFLOPS | 2176 GFLOPS |
| Double-Precision Compute | 33 GFLOPS | 39 GFLOPS | Up to 42 GFLOPS | 62 GFLOPS | ||
| Code Name | Mars | Mars | Mars | Venus | Heathrow | Wimbledon |
As you can see, the Radeon HD 8000Ms actually slot in underneath AMD's Radeon HD 7800M-series in the Q1 product line-up. AMD plans to fix this in Q2, when 7800M- and 7900M-series replacements get the entire portfolio into the Radeon HD 8000M family.
If you've heard rumors about the Venus and Mars parts, and thought they had something to do with the desktop, then you'll be surprised to learn that those are the code names for two mobile GPUs. Venus is one component, while Mars is divided into three families, all equipped with 384 Stream processors, but operating at different clock rates.
AMD does plan to turn features on and off to differentiate its new GPUs, too. For example, the Mars-based Radeon HD 8790M we're previewing does not include support for the company's Video Codec Engine (VCE). Conversely, the Radeon HD 8800Ms, armed with Venus, are expected to include VCE functionality to speed up video encoding and decoding in hardware.
Previewing GCN For The Mainstream: Radeon HD 8790M, Benchmarked
While we would have loved to start by taking a look at one of AMD's Radeon HD 8800M GPUs, the Radeon HD 8790M is its first mainstream GCN-based graphics processor ready for testing. In fact, the company hasn't even started announcing OEM design wins yet.You'd think that would make it hard to benchmark the Radeon HD 8790M. However, we have a bit of hardware in the lab that should allow us to draw a comparison between AMD's next-generation mobile line-up and the one it replaces. The interposer card in the image below drops into a PCI Express x16 slot, and accommodates an MXM module. AMD and Nvidia use these things in their own labs during the bring-up process. They make it possible to do all of the testing needed before an OEM integrates a GPU into its own notebook design.
The interposer solves some problems, even as it introduces others. Let's start with its advantages.
First, and perhaps most important for the scientifically-minded out there, it allows us to maintain a common test platform. Were we to instead benchmark notebooks from competing vendors against each other, we'd have to take different processors, thermal limits, clock rates, memory capacities, and motherboards into consideration. This way, the only things changing are the MXM modules. Moreover, getting our hands on these components allows us to test weeks or months before OEM notebooks start shipping.
Conversely, we're painfully aware that dropping mobile hardware into a desktop environment ignores many of the constraints OEMs face when it comes to integration. We don't get a sense for thermal output or battery consumption during a 3D workload. That makes it easy to create an unrepresentative comparison. See the heat sink on the 8790M? It's quite a bit larger than the 7670M's cooling solution. Could we be facing a match up that never pans out in the real-world? Perhaps, though a 28 nm processor and proven-better efficiency give the GCN-based part headroom that the prior-gen part doesn't enjoy. When we first started this evaluation, AMD told us we were working with a Radeon HD 8770M, and that it was as close to a drop-in replacement for the 7670M as you'd find, matching its TDP. But after GPU-Z indicated that we were dealing with a Radeon HD 8790M, the company corrected itself and confirmed the higher-end part, operating at 850 MHz with a 900 MHz boost state available.
There's no way for us to be certain that the previous-gen part, the part we originally thought we'd be testing, and the 8790M we actually have in the lab would all work in the same notebook, or if their respective thermal and power attributes would preclude one or more from sharing compatibility. So, we're hedging our bets by not involving Nvidia in this discussion, and recommending that you consider the performance we're presenting as a comparison between two distinct models in AMD's line-up, which you wouldn't necessarily find in the same chassis.
The specs on the Radeon HD 7670M match what we are expecting. GPU-Z doesn't fully recognize the 8790M, but it does pick up its maximum 900 MHz boost clock.
Test Setup And Benchmarks
by
Andrew Ku
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| Test Hardware | |
|---|---|
| Processor | Intel Core i5-2500K (Sandy Bridge), 32 nm, 3.3 GHz, LGA 1155, 6 MB Shared L3, Turbo Boost Enabled |
| Motherboard | MSI Z77A-GD80 |
| Memory | Kingston Hyper-X 8 GB (2 x 4 GB) DDR3-1333 @ DDR3-1333, 1.5 V |
| System Drive | OCZ Vertex 3 240 GB SATA 6Gb/s |
| Graphics | AMD Radeon HD 7670M 1 GB GDDR5 AMD Radeon HD 8790M 2 GB GDDR5 |
| Power Supply | Seasonic 760 W, 80 PLUS Gold |
| System Software and Drivers | |
| Operating System | Windows 7 x64 Ultimate |
| DirectX | DirectX 11 |
| Driver | Graphics: Catalyst 9.011 beta RST: 11.5.0.1207 Virtu: 1.1.101 |
| Benchmarks | ||||
|---|---|---|---|---|
| Hitman Absolution | 1280x720, 1600x900, 1920x1080, Low and Ultra Quality Presets | |||
| Far Cry 3 | 1280x720, 1600x900, 1920x1080, Low and High Quality Presets | |||
| The Elder Scrolls: Skyrim | 1280x720, 1600x900, 1920x1080, High and Ultra Quality Presets | |||
| World of Warcraft: Mists of Pandaria | DX11; 1280x720, 1600x900, 1920x1080, High and Ultra Quality Presets | |||
| Battlefield 3 | 1280x720, 1600x900, 1920x1080, Low and Extra Quality Presets | |||
| Call of Duty: Black Ops II | 1280x720, 1600x900, 1920x1080, Normal and Extra Quality Presets | |||
| LuxMark | v2.0, Sala Scene | |||
| CLBenchmark | ||||
Hitman: Absolution  Hitman Absolution BenchmarkThe recent introduction of Hitman: Absolution gives us a new title for our suite with built-in benchmarking capabilities. Not only does it support DirectX 11, but the characters are really well-done. Although this title is available on consoles as well, there are a number of PC-only features (like higher texture resolution, higher shadow map resolution, and increased gesture resolution). DirectX 11-specific additions include global illumination, bokeh, tessellation, Eyefinity support, and HD3D support.  Even at Low quality, the Radeon HD 8790M demonstrates its advantage over the 7670M. With anti-aliasing disabled, it delivers 35% more performance than the 7670M at 1280x720.  The delta increases as resolution goes up, too. At 1920x1080, the Radeon HD 8790M outperforms the 7670M by 45%, delivering fairly playable performance where last generation's part doesn't. Enabling 2x anti-aliasing translates to a roughly 35% advantage favoring the Radeon HD 8790M across the board. At 1280x720, frame rates remain playable, but above that they aren't as viable. We're definitely still looking at mainstream hardware here.   The Ultra quality preset hammers that point home for us. No longer is the story about performance; it's now a matter of basic playability. Even at 1280x720 with no anti-aliasing applied, both mainstream GPUs struggle to serve up a smooth experience. Sure, the Radeon HD 8790M decimates its predecessor. But you're going to need to make some compromises when it comes to gaming on a less expensive low-power platform.   Far Cry 3
Don Woligroski recently published Far Cry 3 Performance, Benchmarked,
and determined that even the Low quality preset looks pretty darned
good. In his performance evaluation, he ran around a specific outpost
during daytime. Because there is no built-in benchmark for Far Cry 3,
we end up with some variation in our results due to user input. At
least we end up with numbers representative of actual game play, though.
We're replicating Don's methodology for benchmarking AMD's mobile
graphics processors.
 At the Low quality preset, the 7670M is fairly playable at 1600x900, and definitely workable at 1280x720. Dips as low as 17 FPS at 1920x1080 render that setting untenable. The Radeon HD 8790M alleviates all of that, serving up anywhere between 50-60% more performance. Even at 1920x1080, the game is fairly fluid. Stepping up to the High quality preset renders the Radeon HD 7670M completely unplayable. The 8790M gets by at 1280x720, but is hampered by demanding graphics at 1600x900 and 1920x1080.  The Elder Scrolls V: Skyrim
More so than Hitman or Far Cry 3, The Elder Scrolls V: Skyrim tends to be platform-bound. That's good news for mid-range mobile graphics processors.
 Using the High preset, we still see that increasing resolution has an impact on each GPU, though. The Radeon HD 7670M is fairly playable at 1280x720, though it drops as low as 20 FPS in heavily-wooded areas. The last-gen VLIW5-based chip gets increasingly choppy as you step up to 1600x900 and beyond. Meanwhile, the Radeon HD 8790M does better at 1920x1080 than the 7670M did at 1280x720. We're comfortable calling all three resolutions playable at this detail level.  The Ultra preset is notably more taxing on graphics hardware. We wouldn't bother trying to enjoy Skyrim on a Radeon HD 7670M-equipped notebook at even 1280x720 using that setting. AMD's Radeon HD 8790M fares better, but still suffers occasional performance dips. |
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