GPU Memory, OPENCL/CUDA in Resolve 1x

Hello,
I am having major issues editing UHD video from my Sony PXW-X70 since the upgrade to Resolve 14 Studio due to the dreaded "GPU Memory Full" error message. I have 3 GB of RAM on my Radeon R9 280X which is lower than the recommended specs.
Using GPU memory monitoring tools, I noticed that even though the card has 3 GB, the program stops working and displays the error message when GPU memory usage reaches 2-2.5 GB. This makes it very difficult to know exactly how much memory is really needed.
I do not need a superfast GPU for complex color grading, I guess just more GPU RAM in order to be able to simply use the software for editing. When I built my new PC, CPU and RAM were the most important (I was planning on using Final Cut Pro), now it seems to have shifted to GPU with Resolve 14. I do not do huge color grading operations but appreciate the power of Resolve when I need it. I am a low end amateur, I do not use Resolve as a Pro. I output to compressed h.264. Because I invested in the Studio version license, I am pretty much stuck with Resolve now and need to find a fix to the GPU Memory Full problem.
Looking at all the information about CUDA vs. OpenCL, it seems like BMD has clearly chosen NVidia and has put more optimizations in place to take advantage of their GPUs vs. AMD. I am open to switch from AMD to NVidia in order to take advantage of all this, but the problem is that an 8GB graphics card equates to a very high end and expensive GPU. Radeon cards with 8 GB are more reasonable, but still. Whereas on a motherboard, one can choose the CPU and memory independently, on a graphics board there is a direct link between the amount of RAM and the GPU class you have to buy. As a consequence an 8 GB graphics card costs a minimum of $300 for a Radeon RX 580 and $410 for an NVidia GTX1070. I wish they made a GTX1050 or RX470 with 8 GB for the DaVinci Resolve market but that's not the case (yet?), or made cards that have RAM slots to allow for upgrades. Until then I am forced to buy more GPU power than I need, just to be able to fit the UHD video I process into the graphics card's memory.
I would prefer a GTX to be able to take advantage of the h.264 and h.265 encoding/decoding acceleration today, but given my budget that forces me to buy a GTX 1050 with only 4 GB or a 1060 with 6 GB. How can I know if 4 or 6 GB of RAM will be sufficient to process UHD video? Has anyone been able to process UHD with 4 GB?
Secondary question, is it possible for BMD to start implementing more OPENCL optimizations in the future that will put Radeon cards on equal levels with GTX cards in terms of h.264/265 acceleration? Is CUDA so unique? Will BMD start supporting h.264 acceleration from Intel chips (quicksync)? If QuickSync or Radeon h.264/265 acceleration are on the roadmap for a future release of Resolve, I could save money and buy a Radeon card with 8 GB of Ram, knowing that I will not miss on the CUDA specific acceleration for too long.
I am sure that I am not the only one facing a potential investment in hardware to support Resolve 14 and up, it would be nice to have an idea of what we should invest in today that Blackmagic Design plans to support in the next versions of their software.
I am having major issues editing UHD video from my Sony PXW-X70 since the upgrade to Resolve 14 Studio due to the dreaded "GPU Memory Full" error message. I have 3 GB of RAM on my Radeon R9 280X which is lower than the recommended specs.
Using GPU memory monitoring tools, I noticed that even though the card has 3 GB, the program stops working and displays the error message when GPU memory usage reaches 2-2.5 GB. This makes it very difficult to know exactly how much memory is really needed.
I do not need a superfast GPU for complex color grading, I guess just more GPU RAM in order to be able to simply use the software for editing. When I built my new PC, CPU and RAM were the most important (I was planning on using Final Cut Pro), now it seems to have shifted to GPU with Resolve 14. I do not do huge color grading operations but appreciate the power of Resolve when I need it. I am a low end amateur, I do not use Resolve as a Pro. I output to compressed h.264. Because I invested in the Studio version license, I am pretty much stuck with Resolve now and need to find a fix to the GPU Memory Full problem.
Looking at all the information about CUDA vs. OpenCL, it seems like BMD has clearly chosen NVidia and has put more optimizations in place to take advantage of their GPUs vs. AMD. I am open to switch from AMD to NVidia in order to take advantage of all this, but the problem is that an 8GB graphics card equates to a very high end and expensive GPU. Radeon cards with 8 GB are more reasonable, but still. Whereas on a motherboard, one can choose the CPU and memory independently, on a graphics board there is a direct link between the amount of RAM and the GPU class you have to buy. As a consequence an 8 GB graphics card costs a minimum of $300 for a Radeon RX 580 and $410 for an NVidia GTX1070. I wish they made a GTX1050 or RX470 with 8 GB for the DaVinci Resolve market but that's not the case (yet?), or made cards that have RAM slots to allow for upgrades. Until then I am forced to buy more GPU power than I need, just to be able to fit the UHD video I process into the graphics card's memory.
I would prefer a GTX to be able to take advantage of the h.264 and h.265 encoding/decoding acceleration today, but given my budget that forces me to buy a GTX 1050 with only 4 GB or a 1060 with 6 GB. How can I know if 4 or 6 GB of RAM will be sufficient to process UHD video? Has anyone been able to process UHD with 4 GB?
Secondary question, is it possible for BMD to start implementing more OPENCL optimizations in the future that will put Radeon cards on equal levels with GTX cards in terms of h.264/265 acceleration? Is CUDA so unique? Will BMD start supporting h.264 acceleration from Intel chips (quicksync)? If QuickSync or Radeon h.264/265 acceleration are on the roadmap for a future release of Resolve, I could save money and buy a Radeon card with 8 GB of Ram, knowing that I will not miss on the CUDA specific acceleration for too long.
I am sure that I am not the only one facing a potential investment in hardware to support Resolve 14 and up, it would be nice to have an idea of what we should invest in today that Blackmagic Design plans to support in the next versions of their software.