I prefer a bigger SSD than going into NVME or M.2, for me we are reaching points where the use of mechanical hdds is mostly for storage, but programs and games are getting bigger, to me 512GB is way to close to what i need, so 1tb for me is now a days what i use.
Now talking strickly about the 950Pro, its probably the best consumer ssd in the market, weather you benefit from it depends on your workloads, what you will gain is very high sequential reads and writes, a little better random 4k over the 850pro, for the average user, this are things he will never notice on the daily bases. Now if your editing software do benefit from high sequentials, go for it, is at fast as you can get atm for consumer drives. Personally i have been waiting for Sata Express to take off, not sure why it hasn't, but in time, if it stays the same, when I move platforms and ill move to M.2 once they cover my storage needs.
About the case, I would suggest the
SilverStone Temjin TJ08-E: MicroATX Evolved, the Asus FanXpert3 should be able to drop the rpms of the AP181 to about 450rpms and it will have very good airflow, coolers like
Thermalright HR02 or
Scythe Ninja4 would be my pick over the Coolermaster 212, they come with very decent fans for what you pay and specially if you are going to be editing and loading the CPU, would be great to have a better CPU cooler with a better fan. I would remove the hdd cage for better airflow and you can still have a single 3.5 hdd on the bottom or you can mount extras on the 5.25 bays, ssds there is a bottom mount but a lot of people have mounted in the bottom of the case or in the back or in 5.25, lots of places to velcro them, not a big deal either.
