VRAM Analysis 2GB vs 4GB - Alien Isolation
With a benchmark technology called FCAT on the following few pages, we will look into Frame Experience Analysis. Basically with the charts shown we are trying to show you graphics anomalies like stutters and glitches in a plotted chart. Lately there has been a new measurement introduced, latency measurements. Basically it is the opposite of FPS.
- FPS mostly measures performance, the number of frames rendered per passing second.
- Frametime AKA Frame Experience recordings mostly measures and exposes anomalies - here we look at how long it takes to render one frame. Measure that chronologically and you can see anomalies like peaks and dips in a plotted chart, indicating something could be off.
We have a detailed article (read here) on the new FCAT methodology used, and it also explains why we do not use FRAPS anymore.
Frametime - Basically the time it takes to render one frame can be monitored and tagged with a number, this is latency. One frame can take say 17 ms. Higher latency can indicate a slow framerate, and weird latency spikes indicate a stutter, jitter, twitches; basically anomalies that are visible on your monitor.
What Do These Measurements Show?
Basically, what these measurements show are anomalies like small glitches and stutters that you can sometimes (and please do read that well, sometimes) see on screen. Below I'd like to run through a couple of titles with you. Bear in mind that Average FPS matters more than frametime measurements. It's just an additional page or two of information that from now on we'll be serving you.
Alien Isolation 2GB vs 4GB
We'll do three tests assisted by FCAT and scale upwards in VRAM. Alien Isolation even at HQ utilized roughly 1.4GB of VRAM. On the next page Thief, which will use almost 4GB of graphics memory and then on the 3rd page we look at Middle Earth: Shadow of Mordor which utilizes over 3 GB of graphics memory. Above, a percentile chart of the 28 seconds @ 2560x1440. In this particular chart we plot FPS and place it in relation to percentiles.
- For the 960 - 50% of the time measured frames is close to 60 FPS. This you can consider the average framerate. You'll notice that the two bars are VERY close to each other. Interestingly enough, 4GB was a tiny hint slower. The next chart is the important one though.
Above, the cards at a resolution of 2560x1440 (WHQD). On this 55 second run the graphics cards manage to remain below 20 ms; as you can see there are no real stutters recorded. This perfect rendering for both cards (frametime wise lower is better).
Especially once you run into VRAM issues (or the lack of it) you could see big spikes in latency as the card is swapping out textures or can't cache shaders etc. But this title uses very little graphics memory. Let's move to the next page where the 2GB card will run out of graphics memory as we pass 2GB and head on-wards to 3 GB graphics memory usage.