You should ask this in a CAD dedicated subgroup. I've been running high-end CAD software (I-DEAS, UG NX, Solidworks) on low to midrange PCs since 2000, and never had any issues. I don't know of any CAD system that supports the high-end features of the graphics cards you specify. There are some advanced rendering packages that might, but those cards aren't necessary. You might just get your pretty picture faster.
If you're going to be running FEA or simulations, just pack as much RAM as you can. 32Gb minimum.
If you graph prime numbers in various ways, you get artifacts like rays or lines. But it's not related specifically to the prime numbers. They're just caused by the composite numbers erasing straight rows of integers, leaving behind straight rows of primes.