The ASUS Radeon HD 7870 DirectCU II is a high-end graphics card with a large dual fan cooler. Though it has an impressive look, it doesn’t have quite what it takes to cool the GPU quietly at full load.
October 15, 2012 by Lawrence Lee
Product | ASUS HD 7870 DirectCU II HD7870-DC2-2GD5-V2 PCI-E Graphics Card |
Manufacturer | ASUS |
Street Price | US$240 |
Recently we reviewed the ASUS GeForce GTX 680 DirectCU II OC, a top-of-the-line graphics card with a large and impressive dual fan heatsink. While it’s a superb video card, as with most cutting-edge PC hardware, it’s a prime example of diminishing returns on investment. The more you pay, the less improvement you get; a US$460 GTX 680 unfortunately doesn’t offer twice as much performance as a card half the price like the Radeon HD 7870. Slower cards tend to almost always give you more bang for your buck until you hit the sweet spot which is actually somewhere around the US$100 mark.
High-End Radeon HD 7000 Comparison | ||||
Model | HD 7850 | HD 7870 GHz Edition | HD 7950 | HD 7970 |
Transistor Count | 2.8 billion | 2.8 billion | 4.3 billion | 4.3 billion |
Die Size | 212 sq. mm | 212 sq. mm | 352 sq. mm | 352 sq. mm |
Shader Units | 1024 | 1280 | 1792 | 2048 |
Core Frequency | 860 MHz | 1000 MHz | 800 MHz | 925 MHz |
Memory Type | 1GB / 2GB GDDR5 | 2GB GDDR5 | 3GB GDDR5 | 3GB / 6GB GDDR5 |
Memory Frequency | 1200 MHz | 1200 MHz | 1250 MHz | 1375 MHz |
Memory Bus | 256-bit | 256-bit | 384-bit | 384-bit |
TDP | 130W | 175W | 200W | 250W |
Street Price (USD) | $170 / $190 | $230 | $300 | $380 / $600 |
The HD 7870 doesn’t represent the best value available but it certainly offers more than it did at release. Launched in March with a MSRP of about US$350, the HD 7870 has since tumbled in price by more than US$100 though it still occupies a mid-to-high position in AMD’s Radeon HD 7000 lineup. Based on AMD’s 28 nm “Pitcairn” architecture, the 7870 die is packed with with 1280 stream processors and a 256-bit memory interface. The reference model calls for a core clock speed of 1000 MHz (making it a “GHz Edition”, a seemingly superfluous naming convention) and 2GB of GDDR5 1200 MHz, to which our ASUS HD 7870 DirectCU II sample conforms.
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Though “DirectCU II” is printed clearly on the box and heatsink shroud, it isn’t the same bulky cooler found on the GTX 680 DirectCU II OC. The moniker describes the style of cooler ASUS uses on most of their cards to differentiate it from reference cooling solutions — it’s not a single, distinctive heatsink model. Compared to the GTX 680’s heatsink, this is a much smaller cooling solution, taking up only two slots in total as the fans are substantially thinner. The layout is also completely flipped around, with fins running down the length of the board rather than widthwise, and heatpipes intersecting them on the perpendicular.
ASUS Radeon HD 7870 GHz Edition Model Comparison | ||||
Model | HD7870-DC2-2GD5 | HD7870-DC2-2GD5-V2 | HD7870-DC2T-2GD5 | HD7870-DC2TG-2GD5-V2 |
Core Clock | 1010 MHz | 1000 MHz | 1100 MHz | 1100 MHz |
Memory Clock | 1210 MHz | 1200 MHz | 1250 MHz | 1250 MHz |
Outputs | 2 x Mini-DP, HDMI, DVI | DP, HDMI, 2 x DVI | 2 x Mini-DP, HDMI, DVI | DP, HDMI, 2 x DVI |
Additional Features | N/A | DIGI+ VRM | N/A | DIGI+ VRM |
Extras | CF cable, VGA adapter, | CF cable, VGA adapter | CF cable, VGA adapter, power cable | CF cable, VGA adapter, Diablo III mouse pad |
To befuddle consumers, ASUS is currently offering four separate versions of the HD 7870 with minor variations in the model number to differentiate them. The D2T‘s are clocked higher than the DC2‘s, at 1100/1250 MHz, while the V2 editions have more advanced voltage regulation circuitry (DIGI+VRM) and trade two mini-DisplayPorts for one regular DisplayPort and an additional DVI connection. Our sample is the HD7870-DC2-2GD5-V2 (in bold in the table above).
ASUS HD 7870 DirectCU II (HD7870-DC2-2GD5-V2): Specifications (from the product web page) | |
Graphics Engine | AMD Radeon HD 7870 |
Bus Standard | PCI Express 3.0 |
Video Memory | GDDR5 2GB |
Engine Clock | 1000 MHz |
Memory Clock | 4800 MHz ( 1200 MHz GDDR5 ) |
RAMDAC | 400 MHz |
Memory Interface | 256-bit |
Resolution | D-Sub Max Resolution : 2048×1536 DVI Max Resolution : 2560×1600 |
Interface | D-Sub Output : Yes x 1 (via DVI to D-Sub adaptor x 1) DVI Output : Yes x 1 (DVI-D), Yes x 1 (DVI-I) HDMI Output : Yes x 1 Display Port : Yes x 1 (Regular DP) HDCP Support : Yes |
Accessories | 1 x CrossFire cable 1 x DVI to D-Sub adaptor |
Software | ASUS Utilities & Driver |
ASUS Features | DirectCU Series |
Dimensions | 01.47 ” x 4.25 ” x 1.54 ” Inch |
PHYSICAL DETAILS
The ASUS HD 7870 DirectCU II is 24.1 cm long measured from the rear panel to the far edge of the circuit board and the cooler adds an additional 2.3 cm to its length. The heatpipes also hang over the edge of the PCB, increasing its effective width by 2.0 cm. The heatsink accounts for 440 grams of the card’s 710 gram total weight.
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TEST METHODOLOGY
Our test procedure is an in-system test, designed to:
1. Determine whether the cooler is adequate for use in a low-noise system.
By adequately cooled, we mean cooled well enough that no misbehavior
related to thermal overload is exhibited. Thermal misbehavior in a graphics
card can show up in a variety of ways, including:
- Sudden system shutdown, reboot without warning, or loss of display signal
- Jaggies and other visual artifacts on the screen.
- Motion slowing and/or screen freezing.
Any of these misbehaviors are annoying at best and dangerous at worst —
dangerous to the health and lifespan of the graphics card, and sometimes to
the system OS.
2. Estimate the card’s power consumption. This is a good indicator of how efficient
the card is, and it affects how hot the GPU runs. The lower the better.
3. Determine how well the card decodes high definition video.
Test Platform
- Intel Core i3-2100 processor, Sandy Bridge core, dual core 3.1 GHz, integrated HD 2000 graphics, TDP of 65W.
- Thermalright HR-02 Macho
heatsink, an early design prototype with a Scythe
Slip Stream 500RPM 120mm fan. - Gigabyte Z77X-UD3H motherboard, Z77 chipset, ATX, PCI-E 3.0.
- Kingston HyperX Genesis memory, 2x4GB, DDR3-1600.
- Corsair Force GT
solid state drive, 120GB, 2.5 inch, SATA 6 Gbps, refurbished. - Kingwin Lazer Platinum
power supply, ATX v2.2, 80 Plus Platinum, 1000W total output, 83A on +12V rail. - Fractal Design Define R3 case,ATX, modified.
- Antec TrueQuiet 120 120mm
fan, two connected to controllable motherboard headers, 1000 RPM, 3-pin. - Microsoft
Windows 7 Ultimate operating system, 64-bit - AMD
Catalyst graphics driver for AMD/ATI based graphics card, version 12.8. - NVIDIA GeForce graphics driver for NVIDIA based graphics cards, version 301.42.
GPUs Compared:
- AMD Radeon HD 5450 – 650 MHz, 512MB GDDR3 @ 900 MHz
- HIS Radeon HD 5550 Silence – 550 MHz, 512MB GDDR5 @ 1000 MHz
- AMD Radeon HD 5570
– 650 MHz, 1GB GDDR3 @ 900 MHz - AMD Radeon HD 6570
– 650 MHz, 512MB GDDR5 @ 1000 MHz - Sapphire Radeon HD 7750 Ultimate Edition – 800 MHz, 1GB GDDR5 @ 1125 MHz
- ASUS Radeon HD 6850 DirectCU – 790 MHz, 1GB GDDR5 @ 1000 MHz
- AMD Radeon HD 6870 – 790 MHz, 1GB GDDR5 @ 1050 MHz
- HIS Radeon HD 5870 iCooler V Turbo – 875 MHz, 1GB GDDR5 @ 1225 MHz
- ASUS Radeon HD 7870 DirectCU II – 1000 MHz, 2GB GDDR5 @ 1200 MHz
- ASUS GeForce GT 430 – 700 MHz, 1GB DDR3 @ 800 MHz
- Zotac GeForce GT 640 ZONE Edition 902 MHz, 2GB GDDR3 @ 891 MHz
- ASUS GeForce GTS 450 DirectCU
– 783 MHz, 1GB GDDR5 @ 902 MHz - Gainward GeForce GTX 560 Ti Phantom – 823 MHz, 2GB GDDR5 @ 1002 MHz
- ASUS GeForce GTX 680 DirectCU II OC – 1020 MHz, 2GB GDDR5 @ 1502 MHz
Measurement and Analysis Tools
- Prime95 stability test to stress the CPU.
- FurMark
stability test to stress the GPU. - GPU-Z to
monitor GPU temperatures and fan speeds. - SpeedFan to monitor system temperatures and adjust fan speeds.
- MSI Afterburner to adjust GPU fan speeds.
- Cyberlink
PowerDVD to play H.264/VC-1 video. - Mozilla
Firefox with Adobe
Flash Player to play Flash video. - Extech
AC Power Analyzer 380803
AC power meter, used to measure the power consumption
of the system. - A custom-built variable fan speed controller to power third party cooler fans.
- PC-based spectrum analyzer
— SpectraPlus with ACO Pacific mic and M-Audio digital
audio interfaces. - Anechoic chamber
with ambient level of 11 dBA or lower.
3D Performance Benchmarks (for low-end/budget graphics processors only)
- 3DMark Vantage
DirectX 10 benchmark. - 3DMark11
DirectX 11 benchmark. - Unigine Heaven 3.0 DirectX 11 benchmark.
- Lost Planet 2 standalone benchmark, Test “A”.
- Aliens vs. Predator standalone benchmark.
- Crysis demo standalone benchmark.
- Sniper Elite V2 standalone benchmark.
Estimating DC Power
The following power efficiency figures were obtained for the
Kingwin LZP-1000
used in our test system:
Kingwin LZP-1000 Test Results | |||||||
DC Output (W) | 65.5 | 90.7 | 149.0 | 199.6 | 251.2 | 300.3 | 400.9 |
AC Input (W) | 81 | 105 | 166 | 211 | 265 | 322 | 426 |
Efficiency | 80.8% | 86.4% | 89.8% | 92.8% | 92.9% | 93.5% | 94.1% |
This data is enough to give us a very good estimate of DC demand in our
test system. We extrapolate the DC power output from the measured AC power
input based on this data. We won’t go through the math; it’s easy enough
to figure out for yourself if you really want to.
Ambient Noise Level
Our test system’s CPU fan is a low speed Scythe that is set to full speed at all times. The two Antec TrueQuiet 120 case fans are connected to the motherboard and are controlled using SpeedFan. Three standard speed settings have been established for testing.
GPU Test System: Anechoic chamber measurements | ||
Setting | System Fan Speed | System SPL@1m |
High (loud) | 1130 RPM | 26 dBA |
Med (quiet) | 820 RPM | 18 dBA |
Low (silent) | 580 RPM | 12~13 dBA |
Note: mic is positioned at a distance of one meter from the center of the case’s left side panel at a 45 degree angle. |
When testing video cards and coolers with active cooling, the low setting will be used. For passive cards and heatsinks, all three settings will be tested to determine the effect of system airflow on cooling performance.
Video Test Suite
Flash 1080p: The Dark Knight Rises Official Trailer #3, a YouTube HD trailer in 1080p. |
Testing Procedures
Our first test involves monitoring the system power consumption as well as CPU and GPU temperatures during
different states, idle, under load with Prime95 to stress the processor, and Prime95 plus FurMark to stress both the CPU and GPU simultaneously. This last state is an extremely stressful, worst case scenario test which generates
more heat and higher power consumption than can be produced by a modern video
game. If the card can survive this torture in our low airflow system, it should be
able to function normally in the vast majority of PCs. Noise levels are measured and recorded as well; if we deem the card’s fan control to be overly aggressive, we can adjust them at our discretion using various software tools.
Our second test procedure is to run the system through a video test suite featuring
high definition clips played with PowerDVD and Mozilla Firefox (for Flash video). During playback, a CPU usage graph is created
by the Windows Task Manger for analysis to determine the average CPU usage.
High CPU usage is indicative of poor video decoding ability. If the video (and/or
audio) skips or freezes, we conclude the GPU (in conjunction with the processor)
is inadequate to decompress the clip properly.
Lastly, for low-end and budget graphics cards, we also run a few gaming benchmarks to get a general idea of the GPU’s 3D performance. We don’t feel this is necessary for high-end models as there are many websites that do this in painstaking detail.
GPU Cooler Testing
Heatsink testing requires only the Prime95 plus FurMark stress test to be used. The fan(s) (if applicable) are connected to a custom external fan controller and tested at various speeds to represent a good cross-section of its airflow and noise performance.
Our GPU cooler test card is an HIS Radeon HD 5870 iCooler V Turbo, a factory-overclocked single GPU card that draws about 236W by our estimates. The stock VRM heatsink is left on for convenience.
TEST RESULTS
Baseline Power with Integrated Graphics:
Power Consumption Measurements: GPU Test System (Intel HD 2000 IGP) | |||
State | Idle | CPU Load | CPU + GPU Load |
Sys. Power (AC) | 36W | 74W | 87W |
Sys. Power (DC) | unknown | 61W | 72W |
System fan speeds: Low Ambient noise level: 10~11 dBA System noise level: 12~13 dBA |
System with Discrete Graphics:
System Measurements: GPU Test System (ASUS HD 7870 DirectCU II) | ||||
State | Idle | CPU Load | CPU + GPU Load | |
Temp | CPU | 21°C | 38°C | 56°C |
PCH | 34°C | 41°C | 51°C | |
GPU | 31°C | 33°C | 91°C | |
GPU VRM | 43°C | 45°C | 93°C | |
GPU Fan Speed | 1080 RPM | 3240 RPM | ||
SPL @1m | 14 dBA | 30~31 dBA | ||
Sys. Power (AC) | 50W | 90W | 264W | |
Sys. Power (DC) | unknown | 75W | 250W | |
Ambient noise level: 10~11 dBA System noise level on integrated graphics: 12~13 dBA Ambient temperature: 22°C |
With our test system fans on our low speed, 12~13 dBA@1m setting, the HD 7870 DirectCU II ran fairly cool and quiet when idle. The fans were spinning at 1080 RPM but they barely made a dent in the overall SPL and the power draw was only 50W AC which is excellent for a high-end GPU. Putting the system on CPU load had only a 2°C impact on the GPU temperature. The addition of a GPU load pushed the fans to 3240 RPM for a total noise level of 30~31 dBA@1m. The fan control wasn’t being overly aggressive though as this measurement was taken after the GPU core had stabilized at 91°C. It was loud, but needed to be to keep the card adequately cooled.
If you only care about idle noise, the HD 7870 DirectCU II is a great choice. Compared to the GPU test system without discrete graphics, the noise level was only 1~2 dB higher, with most of the extra output limited to the 200~500 Hz range. Subjectively, the overall sound was indistinguishable.
On load, the cooler was much louder of course but it also took on a more complex and undesirable acoustic character. The fans became quite whiny and there was also a clearly audible low frequency hum which explains the incredibly sharp tonal peak we observed at ~220 Hz. It doesn’t sound great but we’ve definitely encountered worse.
Noise & Cooling Comparison
Comparison: GPU Test System (Load) | |||
Model | Est. Power Draw (DC) | GPU Temp | SPL @1m |
HIS HD 5870 Turbo GELID Icy Vision @5V | 236W | 89°C | 17~18 dBA |
AMD HD 6870 + GELID Icy Vision @5V | 182W | 80°C | 17~18 dBA |
ASUS GTX 680 DirectCU II OC | 203W | 75°C | 27~28 dBA |
ASUS HD 7870 DirectCU II | 189W | 91°C | 30~31 dBA |
Gainward GTX 560 Ti Phantom | 233W | 88°C | 37 dBA |
System fans on low (12~13 dBA@1m). Ambient temperature: 22°C |
You would expect a dual fan cooler to produce good results but the 7870 is quite power hungry and the DirectCU II heatsink is equipped with rather thin fans. The end result is a rather high GPU temperature and noise level compared to what you’d get with an aftermarket cooler. The GELID Icy Vision paired with a HD 5870, which has a much higher power draw, managed to keep the GPU temperature under 90°C while generating an overall system SPL of only 17~18 dBA@1m.
The ASUS GTX 680 DirectCU II OC has a similar looking heatsink to the HD 7870, but it’ much larger, with more heatpipes and full-sized fans, and it too, was quieter and cooler despite using more power. That being said, the GTX 680 is about double the price of the HD 7870 so it perhaps is more deserving of a beefed up cooling solution.
Power Consumption
The power consumption of an add-on video card can be estimated by comparing the total system power draw with and without the card installed. Our results were derived thus:
1. Power consumption of the graphics card at idle — when Prime95 is run on a system, the video card is not stressed at all and stays idle. This is true whether the video card is integrated or an add-on PCIe 16X device. Hence, when the power consumption of the base system under Prime95 is subtracted from the power consumption of the same test with the graphics card installed, we obtain the increase in idle power of the add-on card over the integrated graphics chip.
2. Power consumption of the graphics card under load — the power draw of the system is measured with the add-on video card, with Prime95 and FurMark running simultaneously. Then the power of the baseline system (with integrated graphics) running just Prime95 is subtracted. The difference is the load power of the add-on card. Any load on the CPU from FurMark should not skew the results, since the CPU was running at full load in both systems.
Both results are scaled by the efficiency of the power supply (tested here) to obtain a final estimate of the DC power consumption.
Note: the actual power of the add-on card cannot be derived using this method because the integrated graphics may draw some power even when not in use. However, the relative difference between the cards should be accurate.
According to our calculations, the HD 7870 DirectCU II consumed about 14W when idle and 189W on full synthetic load. Its load draw is very close to the HD 6870 but it uses almost half as much energy when idle. It’s supposed to be a much faster card though, so these figures are fairly impressive.
Like many previous high-end Radeon graphics cards, playing hardware-accelerated HD video wasn’t nearly as efficient. Measured from the wall, our HD 7870-equipped GPU test system consumed 83W when playing high definition H.264 and Flash video compared to 50W when idle. The culprit seemed to be high clock speeds when the HD 7870’s UVD chip was activated, a common issue we’ve had with past AMD video cards. According to GPU-Z, its core/memory speeds were 450/1250 MHz compared to 300/150 MHz when idle.
All of the AMD/NVIDIA cards from the last three generations had very similar CPU usage during video playback, 1~2% for our 1080p H.264/MKV test clip, and 8~9% for our YouTube HD sample — the 7870 was no exception.
MP3 Sound Recording
This recording was made with a high
resolution, lab quality, digital recording system inside SPCR’s
own 11 dBA ambient anechoic chamber, then converted to LAME 128kbps
encoded MP3s. It’s intended to give you an idea of how our test system sounds
in actual use — one meter is a reasonable typical distance between a computer
or computer component and your ear. The recording contains stretches of ambient
noise that you can use to judge the relative loudness of the subject. Be aware
that very quiet subjects may not be audible — if we couldn’t hear it from
one meter, chances are we couldn’t record it either!
The recording starts with 5~10 seconds of room ambiance, followed by 5~10 seconds
of the GPU test system with its case fans at various speeds. For the most realistic results, set the volume
so that the starting ambient level is just barely audible, then don’t change
the volume setting again.
- GPU test system (on integrated graphics or using a fanless discrete card)
— stock fans on low (580 RPM, 12~13 dBA@1m)
— stock fans on med (820 RPM, 18 dBA@1m)
— stock fans on high (1130 RPM, 26 dBA@1m)
- GPU test system
with ASUS Radeon HD 7870 DirectCU II at one meter
— idle (1080 RPM, 14 dBA@1m)
— load (3240 RPM, 30~31 dBA@1m)
FINAL THOUGHTS
According to credible gaming-oriented review sites like PC Perspective, HardwareCanucks and AnandTech, the HD 7870 is a high-end graphics card that can play most titles smoothly at 1920×1200 resolution with maximum detail, and can comfortably render even higher resolutions if you knock down the image quality settings a few rungs. The general consensus is that it’s roughly 20% faster than the HD 7850 (~US$180) and trades blows with the GeForce GTX 660 (~US$230) with the HD 7870 prevailing slightly at higher resolutions. These two cards seem to offer the best value in the US$200~$300 price range. The HD 7950 delivers an additional 10% performance boost for ~US$300.
The cooler used on the ASUS Radeon HD 7870 DirectCU II looks more impressive than it is. In 2D operation, it’s very quiet and should be completely inaudible in most systems, but with a GPU load it gets quite loud. The fan control behavior is set to prevent the GPU temperature from exceeding about 90°C so it’s not overly aggressive either. The heatsink is designed for high airflow but the fans are a little undersized and probably don’t do it justice as a result. We would classify its cooling performance as adequate but nothing more. If you’re looking for better, potentially quieter cooling from a stock unit, Sapphire and PowerColor have 7870’s with larger fans and Gigabyte offers a massive triple fan model.
The card’s energy efficiency is excellent except when playing video. We estimated the power draw to be only 14W when idle, easily the lowest we’ve seen from a high-end card in some time. On load, it consumed about 189W, a modest amount by today’s standards considering its level of performance. During both Flash and H.264 1080p playback, the power draw was 33W higher than at idle, 15~20W more than the GeForce 560 Ti and GTX 680 — NVIDIA seems to have the advantage in this department. If you watch a lot of video and your system supports Lucid’s Virtu technology, you may want to try using the IGP for video decoding to save power.
Our thanks to ASUS for the HD 7870 DirectCU II video card sample.
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Articles of Related Interest
Prolimatech MK-26 Multi-VGA Cooler
ZOTAC GeForce GT 640 ZONE Edition Fanless GPU
SPCR’s 2012 Graphics Card/Cooler Test System
ASUS GeForce GTX 680 DirectCU II OC
Sapphire HD 7750 Ultimate Edition
Arctic Cooling Accelero Xtreme Plus GPU Cooler
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