What's Real
When it comes to testing the performance of graphics cards, we, as a hardware review site, obviously have a vested interest in getting things right, particularly our testing methodology. We owe it to our readers to give a fair and unbiased opinion of the products we receive for testing and to do that, we often rely on the built-in benchmarking and time demos included so conveniently by game developers nowadays.
Now, benchmarking computer hardware is not exactly held to the same rigorous standards that one would expect from say, a peer reviewed research paper. But we all believe in and adhere to the scientific method of testing, which means our 'observations' or benchmark results are repeatable and as far as possible, devoid of human error at least.
Does this mean that we often use synthetic benchmarks that have nothing to do with any games available out there? Yes. But it also means that if you replicate our test system independently, from the components down to the drivers and benchmark used, you would get similar results. This
reproducibility is one of the main principles of the scientific method
and something that can only be done easily with the use of scripted time demos and other such 'canned' benchmarks that are widely available and hence easy for users to try. We'll even admit that such canned benchmarks are extremely convenient to get a quick and rough idea of a card's capabilities.
Does it mean that this method of testing is perfect? No. As demonstrated by
previous incidents
where companies have tried to 'game' these benchmarks through specific optimizations that do nothing for the actual performance in-game, hardware vendors know all too well the marketing potential of these commonly used benchmarks and have tried to enhance their products' performance in them. Unfortunately, 'real world' testing is also rift with its own inherent problem of subjectivity, which has the effect of reducing hardware performance testing to something akin to a movie or book review. After all, what does a playable level of performance mean for different individuals? Which portion of the game (selection bias?) should be used for the benchmarking? Are the reviewers able to duplicate exactly what they did when 'benchmarking' a particular map?
In case you're wondering why we have just spent so many paragraphs clarifying our testing approach, it's because the subject of 'real world' vs 'canned' benchmarks recently arose again, with HardOCP's article,
"Benchmarking the benchmarks"
, which explains their stand on this subject and as an example, attempts to highlight a seeming flaw with the Crysis in-game timedemo. Obviously, they may have their points about how actual game play performance could be very different from scripted benchmarks that could be manipulated by optimized drivers. However, these 'illegal' optimizations bring about bad publicity when discovered and vendors run the risk of being exposed by eagle eyed tech editors hoping for such a scandal.
In the end, the highly subjective, "highest playable setting" approach taken by HardOCP is useful but this approach fails to give users the relative difference in performance between graphics cards, which those otherwise 'meaningless' numbers reported by benchmarks, give. Not to mention that readers cannot duplicate HardOCP's findings even if they wanted to and basically have to trust that they got it right. Perhaps reading a variety of reviews using both methods of testing (something like your metacritic.com) would give the more accurate overall picture.
So, now that we have raised a topic worthy of further discussion in our forums and such, let's not forget the actual article today, which is about a very mundane, reference model of the Radeon HD 3870 X2 from PowerColor:
PowerColor has stuck to the same compact packaging for its products for some time now and they managed the same for the heavy duty Radeon HD 3870 X2.
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There are no surprises here and if you aren't up to speed on the whole 'two cards are better than one' approach, please check our related links for our earlier articles on this GPU. The specifications for this PowerColor version is as follows:
PowerColor Radeon HD 3870 X2 Technical Specifications
| Graphics
Engine |
- ATI Radeon HD 3870 GPU
(R680)
- 2 x RV670 (666 million
transistors on 55nm fabrication process)
- Core Clock: 825MHz
- 128 shader units (a
total of 640 stream processing units)
- Ring Bus Memory
Controller
- Fully distributed
design with 512-bit internal ring bus
for memory reads and writes
- Unified Superscalar
Shader Architecture
-
640 stream processing units
- Dynamic load
balancing and resource allocation for
vertex, geometry, and pixel shaders
- Common
instruction set and texture unit access
supported for all types of shaders
- Dedicated
branch execution units and texture address
processors
-
128-bit floating point precision for all
operations
-
Command processor for reduced CPU overhead
-
Shader instruction and constant caches
-
Up to 80 texture fetches per clock cycle
-
Up to 128 textures per pixel
-
Fully associative multi-level texture cache
design
-
DXTC and 3Dc+ texture compression
-
High resolution texture support (up to 8192
x 8192)
-
Fully associative texture Z/stencil cache
designs
-
Double-sided hierarchical Z/stencil buffer
-
Early Z test, Re-Z, Z Range optimization,
and Fast Z Clear
-
Lossless Z & stencil compression (up to
128:1)
-
Lossless color compression (up to 8:1)
-
8 render targets (MRTs) with anti-aliasing
support
- Physics
processing support
- Full
support for Microsoft DirectX 10.1
-
Shader Model 4.1
-
32-bit floating point texture filtering
-
Indexed cube map arrays
-
Independent blend modes per render target
-
Pixel coverage sample masking
-
Read/write multi-sample surfaces with
shaders
-
Gather4 texture fetching
- Texture
Arrays
- Dynamic Geometry
Acceleration
-
High performance vertex cache
-
Programmable tessellation unit
-
Accelerated geometry shader path for
geometry amplification
-
Memory read/write cache for improved
stream output performance
- Anti-aliasing features
-
Multi-sample anti-aliasing (up to 8
samples per pixel)
-
Up to 24x Custom Filter Anti-Aliasing
(CFAA) for improved quality
-
Adaptive super-sampling and multi-sampling
-
Temporal anti-aliasing
-
Gamma correct
-
Super AA (CrossFire configurations only)
-
All anti-aliasing features compatible with
HDR rendering
- Texture filtering
features
-
2x/4x/8x/16x high quality adaptive
anisotropic filtering modes (up to 128 taps per pixel)
-
128-bit floating point HDR texture
filtering
-
Bicubic filtering
-
sRGB filtering (gamma/degamma)
-
Percentage Closer Filtering (PCF)
-
Depth & stencil texture (DST) format
support
-
Shared exponent HDR (RGBE 9:9:9:5) texture
format support
- CrossFireX Multi-GPU
Technology
-
Scale up rendering performance and image
quality with 2, 3 or 4 GPUs
- Integrated
compositing engine
- High
performance dual channel interconnect
-
ATI Avivo HD Video and Display Platform
-
Dedicated unified video decoder (UVD) for
H.264/AVC and VC-1 video formats
- High definition
(HD) playback of both Blu-ray and HD
DVD formats
-
Hardware MPEG-1, MPEG-2, MPEG-4/DivX video
decode acceleration
- Motion
compensation and iDCT (inverse discrete cosine
transform)
-
Avivo Video Post Processor
- Color space
conversion
- Chroma
subsampling format conversion
- Horizontal and
vertical scaling
- Gamma correction
-
High Quality Video Post Processing
- Advanced vector
adaptive per-pixel de-interlacing
- De-blocking and
noise reduction filtering
- Detail
enhancement
- Inverse telecine
(2:2 and 3:2 pull-down correction)
- Bad edit
correction
- Two
independent display controllers
- Drive two
displays simultaneously with independent
resolutions, refresh rates, color controls and video overlays for each
display
- Full 30-bit
display processing
- Programmable
piecewise linear gamma correction, color
correction, and color space conversion
- Spatial/temporal
dithering provides 30-bit color
quality on 24-bit and 18-bit displays
- High quality pre-
and post-scaling engines, with
underscan support for all display outputs
- Content-adaptive
de-flicker filtering for interlaced
displays
- Fast, glitch-free
mode switching
- Hardware cursor
-
HDMI output support
- Supports all
display resolutions up to 1920x1080
- Integrated HD
audio controller with multi-channel
(5.1) AC3 support, enabling a plug-and-play cable-less audio solution
-
Integrated AMD Xilleon HDTV encoder
- Provides high
quality analog TV output
(component/S-video/composite)
- Supports SDTV and
HDTV resolutions
- Underscan and
overscan compensation
-
MPEG-2, MPEG-4, DivX, WMV9, VC-1, and
H.264/AVC encoding and transcoding
- Seamless integration
of pixel shaders with video in real
time
- VGA mode support on
all display outputs
- OpenGL 2.0 support
- ATI PowerPlay
-
Advanced power management technology for
optimal performance and power savings
-
Performance-on-Demand
- Constantly
monitors GPU activity,
dynamically adjusting clocks and voltage based on user scenario
- Clock
and memory speed throttling
- Voltage
switching
- Dynamic
clock gating
-
Central thermal management – on-chip
sensor monitors GPU temperature and triggers thermal actions as required
|
| Graphics
Memory
|
- 2 x 256-bit
GDDR3 memory interface
- 1GB DDR3 SDRAM
- Memory Clock = 1800MHz
DDR
|
| RAMDAC |
- Dual
integrated dual-link DVI transmitters
- Each supports 18-,
24-, and 30-bit digital displays at
all resolutions up to 1920x1200 (single-link DVI) or 2560x1600
(dual-link DVI)
- Each includes a
dual-link HDCP encoder with on-chip
key storage for high resolution playback of protected content
- Dual
integrated 30-bit per channel 400MHz RAMDACs
-
Each supports analog displays connected by
VGA at all
resolutions up to 2048x1536
|
| I/O Faceplate
Connectors
|
- 2 x DVI-I connectors
(HDCP Support)
- 1 x mini-DIN connector
|
| Drivers &
Software |
- Driver support for
Windows XP/Vista
|
| Other Information
|
- At
least 550W PSU recommended (750W for dual ATI CrossFireX)
- Native
PCI Express 2.0 x16 bus interface
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