I spent a considerable amount of time recently looking at Workstation grade setups to support a major 3D CAD package as well as support CGI rendering and transcoding.  The major difference is whether you want to support multiple video cards X3 or X4 to support multi-GPU processing (ie.OpenCL).  If not, then a mid-range board (ASUS etc.) that supports ECC (or not) processor is good enough.

The more important question is how much money you want to put into the processor.

If your workload to be mostly single threaded (CAD work), then a mainstream quad processor (with the highest clock speed) is the best.  The motherboard can overclock dynamically to get the best performance.

If your going to use software or application that can work mult-treaded (ie. rendering/transcoding) , then moving up to a server grade processor that supports 8+ cores (and the highest affordable clock speed) is going to make a REAL difference.  When rendering  a single CGI frame takes an hour and you need 300 frames for 10 seconds of video, the seconds/minutes saved add up quickly.

Another approach is to see if your software supports (built-in) clustering capability.  For example Blender can be configured to create (Master/Slave/Client) nodes that can create a rending cluster on to other available machines.  The heavy lifting is off-loaded, saving your workstation to continue on content creation.

Message: 1
Date: Sat, 28 Jan 2017 00:46:42 -0600
From: Trevor Cordes <trevor@tecnopolis.ca>
To: MUUG RndTbl <roundtable@muug.ca>
Subject: [RndTbl] new ECC computer options
Message-ID: <20170128064642.GA5713@pog.tecnopolis.ca>
Content-Type: text/plain; charset=us-ascii

I'm looking for input from anyone in the club who may be knowledgable, 
eyeballing, or has purchased a "workstation" system recently with ECC 
memory.  (Note, ECC is imperative!)  I don't need dual-socket, crazy 
speed, just something like a mid-range modern i7 with modern RAM, slots, 
etc.  (i3 speeds won't cut it.)

By "workstation" I mean it has to have at least one PCIe x16 (full 16 
electrical) slot so it can have a good video card installed (and handle 
upgrades in the future).  So some "servers" will qualify, although most do 
not have a true x16 slot (they'll say x16 but the small print will say x8 
or x4 electrical), especially on the low end.  I also need tower form 
factor, as rackmount will (unless 4U) be a pain to fit cards in, etc.  
Lastly, I really want a DIY setup where I buy the board, cpu, etc 
individually, though if a perfect premade system (i.e. Lenovo) exists that 
fits the bill I might consider it (must use no propreitary form factor 
parts, including mobo & PS).

It's basically impossible since the discontinuation of the Intel 
D975 chipsets (nearly 10 years ago) to do Intel with ECC without buying a 
Xeon CPU.  So I'm probably stuck buying a Xeon CPU and getting slower than 
i7 for double the price.  Ugh.

I'd really love to hear from the AMD nuts out there if there are any good 
AMD options, especially ones that are more enthusiast/desktop oriented 
rather than same-price-as-Xeon competitors.  If I'm going to spend big 
bucks, I'll buy Intel: AMD needs to offer a compelling price advantage to 
pull me over.

I still believe AMD could carve a niche for itself by offering desktop 
enthusiast chips / mobos with ECC at desktop, rather than server, prices.  
Maybe add $50 each to a mobo and cpu as the price premium.  Not the 100% 
premium Intel wants just to get ECC.  (I miss the old days when getting 
ECC was cheap/easy.)  If AMD already has such a thing (I'm hoping!), 
great!

I know I'm not the only one in the club interested in these answers.  P.S. 
being a computer reseller, I don't need prices or store suggestions, I can 
just buy it all wholesale :-)  It's the "this chipset plus that CPU" that 
I'm really looking for.

Thanks!