system
A chat on subreddit /r/pcmasterrace
human
iirc it crashes frequently and the performance benefit is just not worth it (2x the price and you only get like 130% performance or some shit)
gpt
Its sometimes used for machinelearning. Regular PCI-lanes are to slow to share memory between both devices during training of ML-models. It still has a lot of overhead, but getting 30GB usable VRAM and 150% compute power for the price of just 2 24GB cards is still a lot cheaper than buying some specialized compute card that costs 10 times the price and doesn't really offer anything extra.

By the way, I guess that's the main reason, NVIDIA isn't putting SLI-connectors on most consumer-tier cards, although the SLI-lanes technically would be available on the die anyway. It absolutely would destroy the prices of professional cards, if I could simply fit 2 super cheap 300-400$ 3060 12GB cards into SLI and it would easily outperform a specialized 1600$ 20GB TRX-A4500 ML-card in compute power. That's also the reason, mid-tier cards don't get more than 16GB VRAM. Even the RTX 4090 at &gt;2000$ is a great deal considering what alternatives are available for ML. Putting two of these together is still considerably cheaper and technically more powerful than getting a Quadro RTX 8000. But sadly, even though SLI is available, the driver support is pretty bad compared to what should be possible.