Advice from an architect, long time AutoCAD user and system builder - to other architectural CAD users.
Key words to build the system are "rendering" and to a lesser degree "3D"
AutoCAD based products (and Revit too) do not take any signifficant advantage of multicore systems, certainly zero advantage of multui processor sysyems unless you render.
The differnce between rendering and (let's say) rotating 3-d model is as follows.
Rendering: beginning and the end is known to the computer, as you set allthe criteria up front, 100% of a model is in the RAM, so the work can be planned ahead and the load can be spread to as many cores as available. Imagine that the task is to dig 10' wide x 4' deep x 120' long trench Northward from a given location. This can be well planned and you can throw in a lot of workers to do this, and more workers (to a point) the fastest the job will be done. Now rotaing the model: you change the criteria every fraction of a second and the computer has no clue what the next move will be. So it is like telling workers every second to change direction, width and depth of the trench. You simply cannot do this faster by throwing in more hands, workers would quickly trip over each other. So, most "drafting" programs do not use much of multiple cores (AutoCAD can use other cores for regen, redraw and such - makes no real difference). Multicore is still usefull for operating system, background operations and other tasks in hand, but all this usually does not take that much horsepower. I assume that one does not plan to export movie while working on AutoCAD.
A. So if you render, get as many cores, and ram, and ssd space as you can afford (keeping in1 proportion to each other), still paying attention to a reasonably high single core speed. This equals a lot of $$$.
B. you render a little and work a lot with 3d models : get fastest (single core speed) i7 (4 cores/8 threads), 16-32GB RAM, SSD
C. you build 3d models but get them rendered by someone else or on different machine: get fastest (single core speed) i5 (4 cores/4 threads) 16GB RAM, SSD
D. you work on 2d drawings: as suggested by others, get any low to mid range gaming machine and it will do great. I would still get an SSD though.
What did I forget about? Yes the video card! I say following as an AutoCAD junkie since version 9 and one that bought and build systems for my small 7 person firm over the three decades: DO NOT SPEND MONEY ON ANY EXPENSIVE STUFF! Any braging about thousands of dollars spent on professional card comes from ignorance and denial.
MYTH: "Professional card will give you better precision.
REALITY: What? I do snap and offset and I do control the precision while building a model, I do not eyeball. If you render, cheap gaming card may give you artifacts or unforseen effects tough.
MYTH: "Professional card will give you better speed.
REALITY: No, not anymore as Open GL is effectively dead for the AutoCAD, so are the specialized drivers. Use low range to mid range gaming card. the peed now depends vastly on the CPU.
MYTH: "Professional card will give you better reliability
REALITY: Well yes it is not a total myth but I was using great number mid range ggaming cards for years with only one failure. Mid range, low range gaming cards are cheap and I would rather use current technology cheaper card and change it when new technology is available, than stick for years with same old stuff. The FX 3800 that I spent over a $1100 in 2009 a dog crap now (I believe that it was then but I had to try). But it still works 🙂
Go to passmark site to check single core performance for selection of your i7 and i5 (currently Devil's Canyon chips)
Speed of RAM does not matter that much day to day.
SSD speed matters more than RAM speed.
Happy CAD operating!
