Thank you, Alan.
About the PSU, what you say jibes with what I've seen in other people's builds - contrary to the prescription I've seen in a couple of places that actual use should come to about 50 or 60 percent of the PSU's capacity. I will look at the Seasonic you mention.
I've heard that having more cores means less time waiting for blur and sharpening filters; that makes the i7-4930K sound awfully good to me - I wouldn't want to calculate how many hours I've spent waiting for those filters! But maybe the great increase in RAM would diminish those wait times a lot? I have no objection to saving money! I hadn't realized there was a new Haswell CPU available; I'll check it out - and 1150 socket motherboards.
Hi Jim - Each time I get involved in one of these "what should I build" threads I swear never again. And here I am back again.. it must be a sickness.
The term you're looking for in regard to not overbuilding past what makes economic sense is "the point of marginal returns." This is the point where spending more money results in such a small improvement in performance that it doesn't make sense to proceed.
You didn't say what system you're coming from. When I help clients with a build this is the first thing I ask because it helps gauge expectations. For instance if they're coming from a more modern Sandy Bridge quad core and they're really complaining about performance I'll first look at their current system to see if there are any glaring discrepancies. If not we'll need to look at some serious changes. But, if they're coming from a 4-5 year old Core Duo.. man, I know they're going to ecstatic with most any modern system that fits their workflow.
Let's start. About power supplies: You're right, a power supply runs at it's best efficiency, produces cleaner power, and runs most quiet at its 50-60% point. Still, you want a bit of headroom. I also use Seasonic (when I'm not in Japan where I can find Sythe's), their platinum versions, which can actually be set so the fan won't come on under a 50% load. This by itself might make a few bucks more for a larger capacity power supply worthwhile. Still, I'd recommend the Seasonic 850 Platinum.
Next, RAM: It's very important every "bank" of RAM be made from the same type of RAM, same timing, etc.. and ideally the same manufacturer. Easy to do. But if a year later you want to add another "bank" of RAM, all you really need to do is find the same type and timing and things will work great. Ideally, get it all upfront if you can afford it. But you don't have to. More: From your usage requirements 32gb of RAM I think is more than adequate. That would be my recommendation.
Motherboards: When determining motherboards I ask the client if they plan on over clocking (not recommended for serious work) and how many of each port type they need. They might be able to get by with only 5-6 USB3.0 ports and no more than 6 drives and if they don't over clock, then a $150ish MB will do great. If you need a lot of ports and drives and must over clock.. then you'll need the $300-$400 MB's which are built for over clocking and have lots of ports. Why an Asus? I like them and I also like Gigabyte and at the moment Gigabyte offers better economics with more choice. Over clocking and how many ports?
CPU: Based on what you describe as your workflow, the Haswell 4770k will more than do the job. Easily, it won't even max the individual cores. The six cores are more money, require more power, produce more heat, and would largely go underutilized for 98% of its' lifespan. The Haswell being a newer generation that produces a lot less heat, is can do roughly 10-15% more work than Iivy Bridge. So it's really like 4.5 cores vs. 6 if those six are the slower Ivy Bridge. If you did a lot of video then I'd recommend the six core for sure and 64gb of RAM for sure. But you're using PS.
SSD's: I really like the Samsung 840 Pro you chose. Nice. Get one (at least a 256gb) for your system disk, and 128gb for a PS cache. If you're a LR user then match an SSD to about half the size of your catalog and task the PS cache to it as well..
Case: Look at what Lian-li offers. Lian-li is like the Rolls Royce of cases. Well worth the little bit extra when building a system.
HDD: 2tb? With 3 and 4tb so inexpensive.. consider going 3-4tb and consider getting two of them and putting them in a RAID1 using your MB to drive them. If one goes bad, the other takes over and you're saved from disaster.
Video card: Before we go there, can you tell me your video requirements? Is 10 bit important to you? You didn't mention video. I guess I'm not understanding why a workstation card when a much less expensive GTX card will do..
Good luck with your build.