In a somewhat strange move, Nvidia has omitted the TVEN NVENC codec from the feature package of the new GTX 1650 that it just released. With each new architecture of the green, from Kepler, a new codec has been presented. Seeing that the new 1650 uses the same codec that Volta had been a surprise, especially since the rest of the Turing of the 16 series does benefit from the latest NVENC. The codec is a unique solution from Nvidia to lighten the coding tasks to devote the processing power to other tasks.
Between the Volta and Turing codecs there is a difference of 15% performance, which does not take a lot, but of course something to take into account when transmitting live games. An official version of the decision is not yet known, but the most obvious reason is that by opting for an old codec, costs are reduced, however few they may seem. Being a low-end graphic to which the AMD RX 580 is making it so difficult, every small savings is crucial. Another theory is that Nvidia has tried to reduce the number of transistors in the GTX 1650 to improve their energy consumption. It is true that preferring the old NVENC does not make a big difference, but it is possible that it is still relevant.