I am trying to figure out the sweet spot of maximizing FPS of encoding videos into h264/h265. I will be running some videos through Georges Vid.Stab library (https://github.com/georgmartius/vid.stab) to stabilize things like drone of GoPro footage, and others just re-encoding to h265 to reduce filesize / bandwidth used.
I stumbled across the DVE (https://github.com/Sonic-Y3k/dve) project, which is nice except it won't work with stabilizing videos as the process will divide up the original video into many subsets and ask multiple computers to encode them. While they would do the job, when the videos are stitched back together they lose the advantage of the stabilization at the stitching points as they don't have the info needed to say where the start frame "should" be compared to the other servers calculations.
I have also looked at the NVidia Grid, Intel Phi as coprocessors, which would be an option, but I haven't seen anywhere that they are actually supported by ffmpeg at this time.
A GeForce GTX 980 with Maxwell V2 seems like a good option, but I haven't seen any numbers that show the encoding of a file with the GPU accelerator vs without, nor do I know if that is a "good" card or if it is overpriced for what I need, or not enough.
I am currently running a Dell R720xd with 160GB RAM (1333MHz), dual Xeon E5-2690 processors on a RAID 1 with 20TB of storage. I have room for 2 full height / length PCI-E cards, and some half height as well.
I don't mind spending up around $1000 provided the benefits are real.