Overclocking and Testing Methodology


The default clock speeds of the X1800 XT from ATI are 625 MHz core clock and 700 MHZ memory clock, but Asus improves on those quite a bit right out of the box.

Asus Extreme AX1800 XT TOP 2DHTV Video Card Review - Graphics Cards 66

These are the default clock speeds of the Asus AX1800 XT TOP: 695 MHz core and 795 MHz memory.  They are running lower here in these screens simply due to some power management going on. 

Asus Extreme AX1800 XT TOP 2DHTV Video Card Review - Graphics Cards 67

With ATI’s current drivers, the amount of overclocking you can do via the Overdrive feature is pretty limited.  In this case, the fastest we could push the clock to was 700/800, which is barely over the settings that Asus uses by default. 

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.

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

Test System Setup

Each set includes a line graph and a bar graph.  The line graph still shows the performance over the span of time of the benchmark and the bar graph shows the data in a min/max/avg format that many readers like to see and are more comfortable with. 

For our benchmark comparisons, we looked at the Asus X1800 XT TOP against the default clock speeds on the reference ATI X1800 XT we had here as well as the readily available XFX 7800 GTX card that is overclocked at 450/1.25. 

GPU Test System Setup


Asus AX1800XT TOP (695/795)
ATI X1800 XT (625/700)Review
XFX NVIDIA 7800 GTX (450/1.25)Review


Athlon 64 FX-55Review


ATI CrossFire Reference Board
Gigabyte K8NXP-SLIReview

Chipset Driver

5.13 CCC


2 x 512 MB Corsair 3200XL

Memory Timings

2.0 2-2-5

Sound Card

Sound Blaster Audigy 2

Hard Drive

Maxtor DiamondMax 10 300 GB

Operating System

Windows XP Professional SP1



ATI Driver

5.13 CCC

Software tested:

  • Doom 3 v1.3
  • Far Cry v1.33
  • Half-Life 2 Engine 7 (two maps)
  • Battlefield 2
  • Guild Wars
  • FEAR
  • Call of Duty 2
  • 3DMark05
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