Unless he is using an APU, you will not notice the difference in 1600 vs 1866 ram outside of maybe scores on passmark. You can also OC that 1600 to 1866 if you truly wanted to.
That mobo I linked has all he needs and is Crossfire ready if he wants to do so in the future. If he goes Nvidia and wants to SLI than a different board would be needed. He can spend more on one if he wishes but that board I linked is a step above basic that fills all current and future needs without breaking the bank. What features does that Gigabyte have that makes it worth $50 more? LINK
As far as that 8320 vs the 8350 scroll down to 3D modeling and tell me that isn't a big difference. That's something to consider since he said he is also going to be using it for Cad. LINK
That's not to mention the 8350 will reach 4.4 on air fairly easy.
I would much rather put the $50 off that board into a more powerful CPU. The features between it and the one I linked are not anything that's going to increase his overall performance like a CPU will.
A few USB and audio plug ins on a board and 1866 vs 1600 ram is not going to bottleneck a system as bad as a CPU can.
ETA: He would possibly be better served with more memory over faster memory for Cad.
ETA 2: Yep
How Much RAM Should You Buy for a CAD Workstation?
Performance versus Budget
To achieve solid performance within a reasonable budget, that sweet spot today is likely between 6 GB and 16 GB of DDR3 1333-MHz RAM. DDR3 is third generation, dual-data rate memory technology, with Intel’s current platforms centered on 1333-MHz clock frequency — and it’s really your best memory option these days.
Ram speed in Cad doesn't matter as much as size.
This post was edited on 7/5 at 12:18 am