What do you define as "slow"? Are these 3D plans created by some CAD program like CREO? I'll categorize my response in a few different areas that you mentioned. But I think I recall discussing similar topics with you in this
thread.
Memory: Adding RAM to a PC only helps it's multi-tasking capabilities. Which you now have more than enough because even the typical user typically doesn't multi-task enough to even utilize 16GB of RAM. You also didn't mention your operating system. But if you launch your task manager, you can quickly see what your average RAM usage is to give you an idea of where you want to be at. Anything about 90-95% continuous utilization is when one should consider an upgrade in my opinion.
Video Acceleration: The 1080 GTX video card you have is not going to do you any favors in terms of rendering in a 3D design environment. Yes it's a top of the line video card, but it is designed specifically for gaming and associated OpenGL type architectures. For design and development software (i.e. CAD, Pro-E, Revit, etc.) that rely heavily on rendering processes, you want something that is more geared towards Direct3D processing. For that NVidia offers their Quadro line-up of video cards. These cards are designed specifically for enterprise design applications and are multi-threaded accordingly to take advantage of the hardware architecture. AMD offers a similar line of video cards called Fire-Pro.
OS/Storage Drives: You seem to have plenty of power under the hood with that 6-core CPU. But your bottleneck is still likely that front-side bus speed. Not sure what mobo you are using and if it has SATA-3 or SATA-6 interfaces. And what type of OS drive to you presently have? If it's a magnetic rotating drive, then your best bet upgrade that will offer night & day difference in performance is a SSD (typically 2.5" form-factor). These have basically become the norm with regard to budgetary SSDs and are roughly 4 times as fast as a HDD. A PCIe (or NVME/M.2) drive can be up to 7 times as fast as a
SSD! But these are much more expensive and usually smaller capacities for obvious reasons. But there might be some good deals to be had with either option, especially today w/ Cyber Monday. In either case, I believe a faster OS drive will greatly improve your program/OS performance.
Hope that helps! :thumbs: