Overclocking, Testing Methodology and System Configuration

Just because NVIDIA’s partners are saying they weren’t going to overclock the 7950 GX2 in its retail form, that didn’t stop us! 

BFG GeForce 7950 GX2 Review: Dual GPU Video Card - Graphics Cards 78

This is the new NVIDIA overclocking control panel showing the stock speeds on the BFG 7950 GX2 card; 500 MHz core and 600 MHz memory.

BFG GeForce 7950 GX2 Review: Dual GPU Video Card - Graphics Cards 79

Just by hitting the ‘Find Optimal’ button here brought us to a 550 MHz core speed and 700 MHz memory speed; not too shabby for a nearly-NVIDIA-endorsed configuration.  I was able to get an even higher overclock to 615 MHz core and 750 MHz memory, nearly equaling the performance of a 7900 GTX SLI configuration! 

Of course, your mileage will vary and we’ll have to wait and see what other users get with their overclocks to see how this holds up. 

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.  Where 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 precisly 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.

Test System Setup

For our testing comparison, we took a single BFG 7950 GX2 graphics card and tested it against the previous flagship from NVIDIA and BFG, the 7900 GTX OC.  I also decided to see how the GX2 performed against a pair of 7900 GT cards in SLI mode, since the specifications on them were so similar.  Finally, ATI’s showing is comprised of their flagship X1900 XTX graphics card. 

Also, for this article I have still included testing at both 1600×1200 as well as 2048×1526, but instead of separating the results from the two resolutions under two different headers, I have combined them on the same page, broken up by gaming title. 

Test System Setup

GPUs

BFG 7900 GTX OC (670/820) – Review
BFG 7900 GT OC (475/680) – Review
ATI X1900 XTX – Review

Processor

Athlon X2 4800+ – Review

Motherboard

Asus A8N32-SLI DeluxeReview

Chipset Driver

6.85

Memory

2 x 1 GB Corsair XMS3500LL Pro

Memory Timings

6-2-3-2.0

Sound Card

Sound Blaster Audigy 2 Value

Hard Drive

Western Digital SE16 400 GB

Operating System

Windows XP Professional SP1

GPU Driver

91.29 BETA

Power Supply

Silverstone Zeus 650 watt (quad 12V rails)

Software tested:

  • Guild Wars
  • Far Cry
  • Battlefield 2
  • FEAR
  • Call of Duty 2
  • Half-Life 2
  • Half-Life 2: Lost Coast
  • 3DMark06
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