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AMD Radeon HD 6870 and 6850 review

by Tarinder Sandhu on 22 October 2010, 03:00 4.5

Tags: AMD (NYSE:AMD), Sapphire, HiS Graphics

Quick Link: HEXUS.net/qa2nn

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HEXUS.bang4buck and HEXUS.bang4watt

Putting all the numbers into perspective, let's take a closer look at overall performance.

In a rough-and-ready assessment of the cards' bang for buck, we've aggregated the 1,920x1,080 frame-rates for four games, normalised them* and taken account of the cards' prices.

But there are more provisos than we'd care to shake a stick at. We could have chosen four different games, the cards' prices could have been derived from other sources and pricing tends to fluctuate daily, especially for pre-release GPUs.

Consequently, the table below highlight a metric that should only be used as a yardstick for evaluating comparative performance with price factored in. Other architectural benefits are not covered, obviously.

Graphics cards Sapphire Radeon HD 5870 1,024MB HIS Radeon HD 5850 1,024MB HIS Radeon HD 6870 1,024MB Sapphire Radeon HD 6850 1,024MB Sapphire Radeon HD 5830 1,024MB HIS Radeon HD 5770 1,024MB ASUS GeForce GTX 480 1,536MB ASUS GeForce GTX 470 1,280MB ASUS GeForce GTX 465 1,024MB KFA GeForce
GTX LTD OC 460 1,024MB 
KFA GeForce GTX 460 1,024MB POV GeForce GTX 460 768MB OC  EVGA GeForce GTX 460 768MB
Aggregate FPS
(1,920x1,080)
244.6 208.5
222.2
194.3 164.5 144.9
305.1
249.7
204.8
233
197.1
217.3 185.9
Normalised* FPS
(1,920x1,080)
214.1 170.15
183
150.85
116.25 93.45
260.35
201.35
151.2
182.8
145.05
165.95
131.05
Current pricing £295 £215 £190+ £150+ £165 £110 £360 £200 £170 £190 £160 £170 £125
bang4buck
(1,920x1,080)
0.726 0.791 0.963 1.006 0.705 0.85 0.723
1.007 0.889 0.92
0.906
0.976 1.048
GPU power consumption** 139 117 126 97 108 90 244 204 195 202 169 158 130
bang4watt***
(1,920x1,080)
1.54 1.454
1.452
1.555
1.076
1.038
1.067 0.987 0.775
0.905
0.858
1.05 1.008


* the normalisation refers to taking playable frame rate into account. Should a card benchmark at over 60 frames per second in any one game, the extra fps count as half. Similarly, should a card benchmark lower, say at 40fps, we deduct half the difference from its average frame rate and the desired 60fps, giving it a HEXUS.bang4buck score of 30 marks. The minimum allowable frame rate is 20fps but that scores zero.

** the GPU power consumption is derived from subtracting a flat rate of 100W - indicating system power-draw without a card - from the Call of Duty: MW2 load figure. While this figure isn't solely indicative of power pulled by the GPU, as the CPU also throttles up, it's a better metric than using peak system-draw alone.

*** the HEXUS.bang4watt score is a crude measurement of how much normalised performance the GPU provides when evaluated against GPU power-draw that's shown in the table: the former is divided by the latter. We're using the peak power-draw numbers obtained by running real-world Call of Duty: MW2.

Evaluation

First let's examine the Radeon stack. Run on the same driver and with identical settings, the Radeon HD 6870 is actually faster than the more-expensive HD 5850. This is surprising given that it concedes 320 stream processors (shaders) to the older card. AMD's clearly made other subtle tweaks in the transition between Cypress and Barts architectures. Having a 900MHz core speed helps, too.

The Sapphire Radeon HD 6850 performs just shy of Radeon HD 5850. This is even more impressive given significantly lower shading power a speculative retail listing of £150. Should this price come to pass, AMD will have a real winner on its hands. Both Radeon cards understandably do well with respect to the HEXUS.bang4buck and bang4watt metrics.

Looking across to the green team, the rejigging of the benchmarked titles gives NVIDIA slightly higher scores than with previous benchmarks. Focus on normalised performance and the price-reduced GeForce GTX 470 has the edge of HD 6870, while it takes a super-clocked GTX 460 1,024MB card to match the faster AMD card's stock-clocked performance.

One needs an overclocked GeForce GTX 460 768MB or stock GTX 460 or GTX 465 1,024MB in order to keep up with a basic HD 6850. AMD is clearly stronger in the energy efficiency department - just take a look at the bang4watt scores across the board.