One of my concerns with this build however is that this motherboard only has 1 PCI.e 3.0, so were I to get a second GPU for the display I'd have to go with a 2.0 card. It may have to wait, but it's an easy upgrade. Also I may be able to swing a SSD going this route (thanks for the suggestion Joker). This way I get the GPU, a more powerful processor (and I can still network to my current machine for rendering or non-GPU based computation) and 32gb of RAM. The CPUs would be useful, but with the projects I have in mind I think the GPU will be a better buy for me. Thanks for the replies, I decided to go with 1 machine instead of 2. Seek the best of both if you plan to do a lot of sim work and can afford to…and it's always easier to upgrade GPUs over time.
Note, you'll still usually want to cook your final sims on CPU a lot of the time when you're after high quality production results (beyond GPU RAM limits), but GPU cooking is extremely useful when fleshing things out. I've no experience with network batching sims.
CPU MODELS CREATED BY CPUSIM DRIVERS
Obviously sim resolution and setup is important…the 6GB on my GPU appears to be partly wasted with nVidia drivers as they're still stuck (or were anyway, I haven't checked in a while) in 32bit address space… ATI cards probably aren't, but I've no idea regarding their performance vs nVidia compute. Bottlenecks in RAM, not sure, or not noticed, but it's a different world when you aren't relying on disk caching (I have 128GB). The Titan is about x10 faster than the CPUs, which from research appears to be about the same as a (much more expensive) Tesla but note that not all sims support GPU cooking atm. I have a dual Xeon workstation, and cook fluid sims with a 6GB Titan Black (2nd GPU).