@Sibel_X
This is how I run my Premiere set-up:
Samsung 840 EVO SSD partial partition for sole scratch disk purposes (you set the scratch disk priority within Premiere)
Put your source file onto the scratch disk
Edit your video as normal, if you're experiencing real time rendering lag it is in all likelihood the GPU's fault (while editing there should be virtually no data being written to your HDD or SSD) assuming the Mercury Playback engine is functioning with your GTX 760, it is not on the list of supported GPU listings from Adobe:
https://helpx.adobe.com/premiere-pro/system-requirements.html
If Mercury Playback is enabled, and you are experiencing playback lag, turn it OFF. If it is not on, turn it ON, however it still may not function with the 760. The Mercury Playback engine (GPU acceleration) ONLY applies GPU acceleration during the effects and editing portions, it does not accelerate encoding via CUDA or OpenCL. If the Mercury Engine is not active the entire processing load is placed on the CPU.
Once you have finished editing and are ready to export the file to your preferred format, export it to your SSD scratch disk.
Copy the completed file to your HDD storage bank and delete it from the scratch disk.
My GTX 770 could handle everything except 4k, my 2 GTX 580's had a severe amount of trouble editing 1080p 60fps files with heavy effects due to the 1.5GB VRAM limit -4k was horrible, my 970's rip apart anything I load up with any effects.
IMO the Velociraptor is not going to give you any appreciable performance increases. I would return it and upgrade your GPU to one on the supported list of hardware for Mercury Playback, as CUDA acceleration and a substantial amount of VRAM (3GB+) is the only thing that will give you a serious performance boost while editing videos and adding a large amount of visual effects.