Rendering 4K using NVIDIA K6000 or K5200

Hello - my first post on this forum. I'm a newbie to Resolve and want to use it to grade SLOG-3 video from my Sony FS7 camera. I tried a test project using a few clips and applying the Sony LUT (clips were in XAVX-I format (mfx files) and at 300 for the bit rate and UHD resolution. I then went to delivery page and exported them using QuickTime and Grass Valley HQX but was only getting 3 fps. Since the specs on my computer were very good, I talked with Blackmagic Support and they indicated it was my graphics card (dual NVIDIA Quadro K4200's) and recommended the K6000 or the K5200.

Has anyone had experience using the high end NVIDIA cards (K6000 or K5200) in 4K rendering in Resolve and what speeds are you getting?

Also, if I were to install a K5200 and utilize one of my K4200's as a second card for my 2 computer monitors and set that card as "GUI only" (so that Resolve would only recognize the K5200) would that improve render performance in Resolve as opposed to using the K5200 for both monitors and Compute?

My computer specs: Dell Workstation T7910 with dual Xeon 10 core 3.2.Ghz processors, 128GB of 2133 memory, Blackmagic Decklink Extreme 4K 12G card going to a 4K monitor, video drive is 3 - 4TB drives in RAID 0 configuration (giving >460 mbs read/write speeds as measured by the Blackmagic drive speed utility) and the dual NVIDIA Quadro K4200's.

I'm sure my low frame rate rendering is due to the 4K high nitrate as well as the destination codec but was wondering if I could expect better results with the higher end NVIDIA cards.

Thanks in advance for any comments.