Scratch Disks

Hello, How fast should scratch disks be for Premiere Pro, 3D software and Photoshop? Is any SSD sufficient, or are there any recommended minimum read/write speeds? OS and project files are on 970 EVO drives (so, pretty fast) and have 32 GB RAM. Thanks!

I installed a gtx 1080 on pcie 4 and already had a gtx 960 which I put on pcie 2. (which the gtx worked fine before installing gtx 1080) It reads the gtx 960 but not the gtx 1080. I installed latest drivers. Still don't see gtx 1080 in device manager. I looked at a computer power calculator and...