PowerColor Radeon HD 7870 Myst Edition Crossfire Reviewccokeman -
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PowerColor Radeon HD 7870 Myst Edition Crossfire Testing:
Here lately frame time testing along with measuring true FPS output to the display with tools such as NVIDIA's FCAT (Frame Capture Analysis Tools) suite have really gained a lot of traction to identify some of the problems associated with running a multiple GPU solution. Ultimately showing who has done their homework in regards to delivering the smoothest game play for the end user. The resolution used is 1920x1080 with comparable run times. Let's start off here with the first game in our test suite.
Looking at the percentile chart we see that both card combinations deliver similar performance in this game from top to bottom and even at the 99th percentile. The frame time data shows both combinations have some latency spikes throughout the game but more heavily biased towards the HD 7870 Myst Edition due to AMD's drivers. Hopefully the frame smoothing drivers AMD is promising make it out sooner than later. Comparing the observed versus captured FPS data you can see a significant amount of dropped frames in this game. With all of the runt and dropped frames taken out of the equation what you will see is a pair of cards that deliver FPS performance within 5FPS of each other with a little less stuttering from the green camp.
In Crysis 3 the GTX 660Ti is giving a smoother game play and higher average FPS. The percentile charts shows the HD 7870 Myst Edition in Crossfire falls off sooner as the FPS spikes are pulled out of the equation. The frame time chart shows that the HD 7870 Myst Edition Crossfire combination has more latency spikes over 30ms contributing to jittery game play. Again we see that runt and drop frames plauge this combination. The FPS chart shows 60 seconds of each run by combinations and how the impact of runt and drop frames influence game play.
Looking at the percentile chart the game play of the HD 7870 Myst Edition in Crossfire take a big performance hit as the FPS spikes are removed from the results. Frame time latency spikes almost across the entire run but for the most part stay under 20ms so you have to work to see any stuttering. In this game we see a tremendous amount of runt and drop frames for the HD 7870 Myst Edition Crossfire combination. FPS results overall when runts and drops are removed have the GTX 660Ti delivering an overall higher level of game performance.
Batman Arkham City:
What you want to see here in the percentile charts is a line that runs almost straight across without a large drop off in FPS as the time window expands. Throughout the run the GTX 660Ti combination delivers a higher FPS level without the large latency spikes seen by the Crossfire HD 7870 Myst Edition. Looking at the run charts you can see the significance of the dropped and runt frames on the final FPS numbers.
Here we see a large drop off in performance initially with the FPS almost leveling out on the HD 7870 Myst Edition Crossfire setup. Frame latency is significantly worse than we see with the NVIDIA combination but the FPS is runnning high enough and the oscillations so small that the stutter is imperceptible. The HD 7870 Myst Edition Crossfire setup shows a ton of runt and dropped frames in this game delivering many more FPS through the card than are actually displayed long enough to be noticed.
Let's take a look at the rest of the test suite and see if we see the same challenges.