system
A chat on subreddit /r/pcmasterrace
human
Not necessarily. One advantage Nvidia has over AMD is that SLI can be forced onto most games even if they don’t support it. This only works for AFR mode, but in that mode you practically have two cards churning out alternate frames twice as fast. In practice, the cards sometimes have arguments over who goes first, causing out of sequence renders which results in microstutters.
gpt
The reason AFR doesn't work is due to temporal effects. That means some rendering algorithms use the previous frame(s) to compute the next one. If that was done by the other GPU (with AFR that's 100% the case), you need to copy that over, which causes synchronization between the GPUs, thus causing a stall (GPU can't work, it has to wait for data to arrive). Stalls like this cause variance in frame times, which manifests itself as microstutters.