I’ll try to shed a little light as far as I see it.
Evolution of Nvidia GPU hardware (Kepler based devices so like 3/2012) brought changes to the drivers that Nvidia supplies. Since new technology has been out for several years, it appears Nvidia with 340.43 and newer drivers ,the CUDA video encoding function was dropped on their GPUs with CUDA capability scores below 3.0 (essentially below 650 series), the drivers now support only their new NVENC encoding technology. NVENC encoding is only capable with Kepler based GPU's, so 650+ series. NVENC is Nvidia's newer hardware core that performs video encoding, essentially CUDA's replacement.
However, to my knowledge, PD(any version) currently does not support NVENC, hence the issues. So for CUDA hardware encoding one needs to stay with the older driver. Don’t confuse CUDA support with OpenCL, two different items. The new drivers with PD12 and PD13 still support OpenCL hardware acceleration based on what I’ve seen (Pref > HA > OpenCL). Just not hardware encoding (Produce > Fast video rendering technology > Hardware video encoder).
Very unfortunate this is how things unfolded. I’m not sure how CL claims "CyberLink has built strategic partnerships with leading CPU and GPU providers and a solid reputation for delivering high-quality, interoperable, and fast time-to-market solutions that keep our OEM partners from top PC brands on the leading edge. "
http://www.cyberlink.com/prog/company/press-news-content.do?pid=3647 and then leaves the user community hanging. I had posted the same in this thread,
http://forum.cyberlink.com/forum/posts/list/39967.page#206632 , I guess it was passed to CL, not that that does the current user community much good. It would appear to me, 3/2012 technology for a strategic partnership should not have caught anyone off guard, especially in a PD13 release and at least a patch for PD12 when Nvidia released the new CUDA less drivers, 6/2014.
Will Nvidia bring back CUDA support to old cards and new drivers releases, my guess, probably not, that's usually how basic technology advancement occurs. Not too many places to read your 3.5 inch floppy these days, let alone my stack of 5 1/4 and a few 8 inch. It still does leave a grey area for those users with pre 650 cards no doubt, but that's only a minor upgrade cost.
I disagree with the context of the statement that it's not only CL PD. Yes it affected all hardware encoding, HOWEVER, many encoders that I use already support NVENC so it's not a major impact for those.
If you want to know your CUDA capability for your card, see
https://developer.nvidia.com/cuda-gpus
Jeff