GPUZ, System Setup and Testing Methodology

With the HD 3870 X2 card, AMD essentially took two RV670 GPUs, downclocked them slightly and slapped them on a single PCB for “CrossFire-on-a-card.”  The R700 is essentially the same design as we saw on the previous page; but this time AMD didn’t downclock the GPUs:

AMD Radeon HD 4870 X2 2GB Preview - R700 a bit early - Graphics Cards 91

Though there are some bugs on the GPU-Z screen shot, you can see that the core clock is running at 750 MHz while the GDDR5 memory is running at 900 MHz – the same speeds the single GPU HD 4870 512MB card runs at.  AMD is obviously serious about getting as much performance out of their GPUs as possible and would we would likely see an HD 4850 X2 card at some point too – much like we saw the HD 3850 X2 1GB card from ASUS this year. 

Testing Methodology

Graphics card testing has become the most hotly debated issue in the hardware enthusiast community recently.  Because of that, testing graphics cards has become a much more complicated process than it once was.  Before you might have been able to rely on the output of a few synthetic, automatic benchmarks to make your video card purchase, that is just no longer the case.  Video cards now cost up to $500 and we want to make sure that we are giving the reader as much information as we can to aid you in your purchasing decision.  We know we can’t run every game or find every bug and error, but we try to do what we can to aid you, our reader, and the community as a whole.

With that in mind, all the benchmarks that you will see in this review are from games that we bought off the shelves just like you.  Of these games, there are two different styles of benchmarks that need to be described.

The first is the “timedemo-style” of benchmark.  Many of you may be familiar with this style from games like Quake III; a “demo” is recorded in the game and a set number of frames are saved in a file for playback.  When playing back the demo, the game engine then renders the frames as quickly as possible, which is why you will often see the “timedemo-style” of benchmarks playing back the game much more quickly than you would ever play the game.  In our benchmarks, the FarCry tests were done in this matter: we recorded four custom demos and then played them back on each card at each different resolution and quality setting.  Why does this matter?  Because in these tests where timedemos are used, the line graphs that show the frame rate at each second, each card may not end at the same time precisely because one card is able to play it back faster than the other — less time passes and thus the FRAPs application gets slightly fewer frame rates to plot.  However, the peaks and valleys and overall performance of each card is still maintained and we can make a judged comparison of the frame rates and performance.

The second type of benchmark you’ll see in this article are manual run throughs of a portion of a game.  This is where we sit at the game with a mouse in one hand, a keyboard under the other, and play the game to get a benchmark score.  This benchmark method makes the graphs and data easy to read, but adds another level of difficulty to the reviewer — making the manual run throughs repeatable and accurate.  I think we’ve accomplished this by choosing a section of each game that provides us with a clear cut path. We take three readings of each card and setting, average the scores, and present those to you.  While this means the benchmarks are not exact to the most minute detail, they are damn close and practicing with this method for many days has made it clear to me that while this method is time consuming, it is definitely a viable option for games without timedemo support.

The second graph is a bar graph that tells you the average framerate, the maximum framerate, and the minimum framerate.  The minimum and average are important numbers here as we want the minimum to be high enough to not affect our gaming experience.  While it will be the decision of each individual gamer what is the lowest they will allow, comparing the Min FPS to the line graph and seeing how often this minimum occurs, should give you a good idea of what your gaming experience will be like with this game, and that video card on that resolution.

Our tests are completely based around the second type of benchmark method mentioned above — the manual run through.

System Setup and Comparisons

We only had the chance to run a few games with the card in our preview requirements but I compiled the most important comparisons for you: one for AMD cards and one for NVIDIA cards.  First you’ll see how the HD 4870 X2 compares to a single Radeon HD 4870 512MB card, a pair of standard HD 4870s in CrossFire mode and the Radeon HD 3870 X2 dual-GPU card from the previous generation.  For NVIDIA’s comparisons you’ll find the HD 4870 X2 2GB compared to the new BFG GeForce GTX 280 1GB, GTX 260 896MB and 9800 GX2 1GB cards. 

Test System Setup


Intel Core 2 Extreme X6800 – Review


EVGA nForce 680i MotherboardReview
Intel X48 Motherboard (for CrossFire testing)


Corsair TWIN2X2048-8500C4

Hard Drive

Western Digital Raptor 150 GB – Review

Sound Card

Sound Blaster Audigy 2 Value

Video Card

AMD Radeon HD 4870 X2 2GB
AMD Radeon HD 4870 512MB
BFG GeForce GTX 280 1GB
NVIDIA GeForce GTX 260 896MB
XFX 9800 GX2 1GB

Video Drivers

NVIDIA Forceware 177.34 Beta
AMD Catalyst – 8.5
Power Supply PC Power and Cooling 1000 watt

DirectX Version

DX10 / DX9c

Operating System

Windows Vista Ultimate 64-bit

  • Bioshock
  • Call of Duty 4
  • Crysis
  • 3DMark Vantage

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