Sapphire Radeon HD 7950 OC Review

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Sapphire Radeon HD 7950 OC Review

AMD’s reference HD 7950 board sets its core clock at 800MHz and memory at 1,250MHz, using the default cooling system. Sapphire takes this reference board, adds dual 12cm fans, and juices the core clock to 900MHz. The memory clock remains at 1,250MHz—but that’s 3GB of 1,250MHz GDDR5. Priced at around $480, it’s worth seeing how the card compares with Nvidia’s GTX 580. Note that we’ve also included results from the XFX Radeon HD 7970 for your reference, but excluded that card from the direct comparisons.

For direct comparison we turned to two different versions of the GTX 580—the slightly overclocked EVGA GTX 580 SC with 1.5GB of GDDR5 and the ultra-beefed-up EVGA GTX 580 Classified with 3GB of video RAM—as well as the XFX Radeon HD 7950 Black Edition reviewed next.

The Sapphire card ships with a slight memory bandwidth disadvantage compared with the XFX card (5GB per second versus 5.5GB/s) due to running its GDDR5 frame buffer at the reference clock speed. This shows up in a few benchmarks, where the Sapphire card places just a little behind the XFX card, but the differences are pretty small.

Sapphire slaps dual fans and a higher core clock on AMD’s new Radeon HD 7950.

Like the XFX card, Sapphire uses a nine-blade fan design for the two fans, but the overall look of the card suggests hints of Chobham armor, unlike the XFX card’s more streamlined, clean appearance. Output ports are standard: a pair of Mini DisplayPort connectors, one HDMI 1.4a port, and a dual-link DVI connector.

Overall noise levels are low, despite the dual fans, yet the card seems slightly noisier than either the HD 7970 reference card or the XFX HD 7970 Black Edition reviewed earlier. It may be that the Sapphire HD 7950 GPU is working harder to hit good frame rates, or the cut-down GPU is running a little hotter than the HD 7970s, which are probably binned parts.

The card did win out on idle power. System idle power is a scant 115W, lower than any high-end card we’ve tested, including AMD’s previous HD 6970. The Sapphire card only needs a pair of 6-pin connectors; total system power pushes up to just to 288W, making the Sapphire HD 7950 OC the most power-efficient of all the high-end cards. You could probably run this card with a good 500W power supply, or even a pair of them in CrossFireX with a good 700W unit.

The Sapphire card costs a little less than the XFX card, idle power is a little lower, and Sapphire doesn’t skimp on the display adapters. That makes it a pretty good deal, given its overall performance level compared to the much hotter and more power-hungry GTX 580s.

Sapphire Radeon HD 7950 OC

Venice, Italy

Excellent performance for this price range; very power efficient; 900MHz core clock

The Venetian Hotel

Just a bit noisier than the 7970 (but much quieter than GTX 580s); slightly lower memory clock than the XFX model

10

BENCHMARKS

Sapphire HD 7950 OCXFX HD 7950 Black Edition
XFX Radeon HD 6970EVGA GTX 580 SCEVGA GTX 580 ClassifiedXFX Radeon HD 7970 Black Edition
Price                
$480$490
$350$480$560$600
3DMark 11 Perf
7,475
7,5565,7506,7477,3218,393
3DMark Vantage Perf
31,26931,33124,45326,93628,55932,813
Unigine Heaven 2.5 (fps)
2828
17222329
Shogun 2 (fps)26
26
19222429
Far Cry 2 / Long (fps)
90
92
758592100
HAWX 2 DX11 (fps)
111113
73120128120
STALKER: CoP DX11 (fps)
33
33
25282939
Just Cause 2 (fps)
44
45
31414850
Batman: Arkham City495136454753
Metro 2033192014151718
DiRT3545544505564
Core / Memory Clocks900 / 1250900 / 1375880 / 1375797 / 1013855 / 10531,000 / 1,425
System Power @ idle (W)115119126140140124
System Power @ full throttle (W)288290296344385349

Best scores are bolded. Our test bed is a 3.33GHz Core i7 3960X Extreme Edition in an Asus P979X Deluxe motherboard with 16GB of Corsair DDR3/1600 and an AX1200 Corsair PSU. The OS is 64-bit Windows Ultimate. All games are run at 2560x1600 with 4x AA except for the 3DMark tests.

SPECIFICATIONS

Radeon HD 7950
Radeon HD 7970
Manufacturing Process
28nm28nm
Transistor Count
4.31 billion4.31 billion
Reference Core Clock
800MHz925MHz
Frame Buffer
3GB GDDR53GB GDDR5
Memory Clock1,250MHz1,375MHz
Memory Data Rate5.0 gigapixels/s5.5 gigapixels/s
Memory Bandwidth240GB/s264GB/s
Memory Bus384-bit384-bit
Stream Processors1,7922,048
Compute Performance2.87 single-precision TFLOPs3.79 single-precision TFLOPs
Texture Units112128
Texture Fill Rate (peak)89.6 gigatexels/s118.4 gigatexels/s
ROPs3232
Z/Stencil128128
Maximum Board Power200W250W
Idle Power (active)15W15W
Idle Power (long dark)3W3W

 

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