You do not want to boot off the SM951, save this very fast SSD m.2 connector for project,cache and media, your 850 Pro is all you need for Boot/OS/Applications. Do you know that the i7-5820 is a PCIe crippled chip? It only has 28 lanes. Now that probably might be enough for starting as it looks like you will only be using 16 + 4 initially. Your motherboard can support two GPU's but you do not have enough lanes from that chip to properly use two GPU's
Yes, it is possible to get by with 128 GB SSD for boot, but you have to carefully plan and control your User data see this Tweakers Page
asus and gigabyte have the best QA, so unless you need/want the MSI, you may want to consider the others.
gpu load will vary on the media, fx, timeline (multi-cam), and lumetri color effect. if using the lumetri color effect, the gtx 960 would be the minimum i would recommend. the gtx 960 should be faster than the gtx 760. the gtx 960 uses new architecture, making it hard to compare cuda cores and memory bandwidth vs older generation cards.
I did know that about the 28 lanes, thank you. I figured the 16+4 would be fine for now. Once this thing starts making money if I really have to have more than 28, I'll bump to the 5960 (or whatever is new then).
I'll just go with the 256GB to boot. No real reason to cut corners there; it isn't something I can just pop out and replace easily if I find 128GB falls short.
>asus and gigabyte have the best QA,
I've had good luck with both in the past.
Suggestions for MB? I think I'm down to researching that now but a starting point wouldn't go amiss. Is there one with a second M.2 slot?
i would look at the motherboards for features, to choose one. if you ever plan on overclocking, you will want a medium to high end one.
im not sure if there are any with two m.2's. there was an asus board that came with an extra pcie adapter though. adapters can be bought extra, so can still consider other boards if another one has the features you need. you can also consider getting a pcie ssd like the intel 750 instead of the samsung m.2. the intel 750 is a bit more expensive, has 400gb and 1tb version. also has a heatsink and uses the new nvme protocol.
my concern is, you didn't want to spend extra money on the video card, the gtx 970 if no boost to performance. these super fast ssd are sorta the same thing, alot more expensive and may be performance overkill. the samsung 850 pro as OS/apps drive like you first had listed, should work fine.
Maybe I wasn't clear in my understanding. From what I had read, I thought that the drive speed/transfer speed was the big bottleneck to smooth playback. I read about GPUs that were lighter weight than the GTX960 barely working under quad core processors and users being told their drives were too few, too slow or configured poorly trying to I/O on the same channel. If the M.2 drives are overkill for what I'm doing, I'll spend that money on something else and buy a more balanced drive for the hardware, I'm just not sure what.
My budget for the box is around $2500. I have monitors and keyboards and such already. And I can go a little more if there is a Good reason.
the cpu/gpu/drive usage will vary depending on media and timeline, so there will be variations between projects and computers as to what the bottleneck is. unlike the media drive, the os/app drive mostly helps open the program faster, not much when the program is open. depending on the project and media, the m.2/pcie ssd's are solid options when all the media and cache can fit on a single one.