Review: ATI Radeon HD 3870 X2 - getting back in the game

by Tarinder Sandhu on 28 January 2008, 10:41

Tags: AMD (NYSE:AMD)

Quick Link: HEXUS.net/qaleg

Add to My Vault: x

HEXUS.bang4buck, power-draw



HEXUS.bang4buck - new suite.

In a rough-and-ready assessment of the cards' bang per buck, we've aggregated the 1,920x1,200 frame rates for the three new and three old games, normalised them* and taken account of listed the cards' prices.

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

Consequently, the table and graph 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 ATI Radeon HD 3870 X2 1024MiB ATI Radeon HD 3870 512MiB ZOTAC GeForce 8800 GT 512MiB AMP! Edition MSI NX8800GTS-T2D512E-OC NVIDIA GeForce 8800 GTX 768MiB
Actual aggregate marks at 1920x1200 173.66 107.04 153.55 165.44 156.75
Aggregate marks, normalised*, at 1920x1200 129 82.76 118.16 124.07 124.04
Current price £279 £149 £189 £209 £235
HEXUS.bang4buck score at 1920x1200 0.462 0.555 0.625 0.594 0.528
Acceptable frame rate (av. 60fps) at 1920x1200 No (ET, LP) No (CoH, ET, LP) No (ET, LP) No (ET, LP) No (ET, LP)


* 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 bang4buck score of 30 marks. The minimum allowable frame rate is 20fps but that scores zero.

As an example, should a card score 120fps we treat it as 90fps as only half the frame rate above 60fps is counted for the bang4buck - this is the formula: (120-((120-60)/2)). Similarly, should it score 30fps, we count it as only 15fps: (30+((30-60)/2)).

The reasoning behind such calculation lies with playable frame rates.

Should card A score 110fps in a benchmark and card B 160, then card B would otherwise receive an extra 50 marks in our bang4buck assessment, even though both cards produce perfectly playable frame rates and anything above 60fps is a bonus and not a necessity for most.

Similarly, without our adjustments, the aggregated bang4buck total for two very different cards would be identical if, in a further benchmark, card A scored a smooth 70fps and card B an unplayable 20fps. Both would win marks totally 180, yet the games-playing experience would be vastly different.

A more realistic (and useful) assessment would say that card A is better because it ran smoothly in both games - and that view would be accurately reflected in our adjusted aggregation, where card A would receive 150 marks (85+65) and card B 100 (100+0).

In effect, we're including a desired average frame rate, in this case 60, and penalising lower performance while giving frame rates higher than 60fps only half as much credit as those up to 60fps. If this doesn't make sense or you have issue with it, please hit the HEXUS community.

Here's the HEXUS.bang4buck graph at 1920x1200.



The graph divides the normalised score by the price.

Radeon HD 3870 X2 1024MiB performance is, on balance, the best on test so why the low-ish HEXUS.bang4buck score? The simple answer is that whilst it is the fastest card, albeit only marginally, the £279 asking price is significantly higher than the GeForce 8800 GT and GTS 512s. Putting it another way, those cards are close enough in performance but are cheaper. You can also add a second and run SLI right now, without having to wait for a supporting driver.

Old suite - XP

Graphics cards ATI Radeon HD 3870 X2 1024MiB NVIDIA GeForce 8800 GTX 768MiB
Actual aggregate marks at 1920x1200 411.09 305.79
Aggregate marks, normalised*, at 1920x1200 295.55 242.9
Current price £279 £235
HEXUS.bang4buck score at 1920x1200 1.059 1.033
Acceptable frame rate (av. 60fps) at 1920x1200 Yes Yes




Looking at the older suite, the graph shows that whilst the 'X2 provides greater-than-GTX performance, its £40 price premium simply offers linear gains: you receive around 20 per cent more normalised performance for paying around more. Further, the GeForce 8800 GTX is hardly slow in any of the benchmarks, either.

Power-draw

The Radeon HD 3870 X2 drew around the same under-load wattage, at the mains, as a GeForce 8800 GTX and twin Radeon HD 3870s in CrossFire. That's to be expected given the nature of the card.