First build in 10 years! Help to a professional animator

I personally wold go for a 750 watt seasonic unit. 650 at the minimum due to wanting to overclock and running that big GPU. 520 is likely enough but probably barely and seems odd in such a high end build.

Also, if you can afford it (and fit it into the case) the Noctua D15 or one of the Phanteks dual 140mm heatsinks would be a better choice. Usually overkill for a quad core but you are working with 6 cores.

Not to worry. I understand the need to balance cost and performance. Since you do need the SSD's, and someone pointed this out in your other post, you will want to stick to better ones than the Adata. They're the cheapest, but you really get what you pay for, and your work is going to need reliable drives. Absolute lowest end I'd go is the OCZ Triton 150, a better step up would be the Sandisk X400, a step up from there would be the Samsung 850 Evo, and finally a Samsung 850 Pro. There are better performing options that your work would actually take advantage of like the Samsung 950, but they're not going to fit in your budget.

As for the cabinet/cooler/ram issue, here's the deal. If you go with an air cooler for overclocking, you will need a cooler that is better than stock. Most of the big air coolers will start to overlap the RAM slots of the motherboard. Depending on the cooler, the height between the motherboard and the cooler will vary. Depending on the cooler, some times this can be fixed by adjusting the height of the fan. Adjusting the fan height raises the overall height of the cooler, but your cabinet allows for coolers up to 180mm tall so you have plenty of room for adjustment. However sometimes the cooler itself will block off after a certain height. This means you will need RAM that can fit under that height. The Noctua NH-D15 is one of the best big air coolers on the market, however you have to either have ram under 32mm in height (hard to find) or adjust the fan up 10mm or so. With your cabinet that's not a problem, as the extra 10mm or so you'd need would only bring the overall height of the cooler to 175mm. But it is also a very heavy fan, so care has to be taken when moving the cabinet around. The Cryorig R1 Ultimate is a similar design, but has a slightly better RAM clearance of 35mm (a bit easier to find) also with an adjustable fan height (would raise the overall height to about 178mm so cutting it close), is cheaper, is lighter and only performs a few degrees worse. Now if you decided you didn't want to overclock, you could get a cooler like the Cryorig H5 universal and use any RAM you like since those models don't overlap the RAM slots.

If you go with a water cooled solution, the price will be higher for the cooler. Usually start around $100 US for a AIO solution like the one I linked, but allows you to use any RAM height modules that you'd like. You can of course go with a higher end one, like the person in your other post pointed out. It would cool better but it also runs over double the price. That's not to say its bad at all, I just don't think it fits in your budget.

Something to keep in mind with all this is you can always upgrade your system over time. Yes it is absolutely easier to start it all out the way you want it, but you add to it. Getting a normal cooler for now and overclocking later would allow you to spend less on a cooler and throw that extra cash at better SSDs so your performance doesn't suffer in the mean time.

Also as for the question in your other thread about Windows. Yes you can load it form a USB. However unless you buy it already on a USB drive, which is available for retail copies, you'll still need access computer with a DVD drive to create a USB boot drive to put the Windows install on. If you're doing Windows 10, I believe you can download a utility and the Windows ISO directly and bypass the need for a DVD drive.