Very solid setup.
I would use a Scythe Mugen 3 or Ninja 3 and two Scythe S-Flex 120mm 800RPM fans instead of the Noctua cooler and the fans that come with the case. That's more of a minor twaek the system should be very quiet the way you laid it out.
I think the Seasonic PSU has enough power, but does it have a 6-pin PCIe power connector?
If the drive cage is prone to rattling a 2.5" drive is a good idea. I currently use a Lian Li case and the drive cage rattles a bit, too. If you can eliminate that noise the computer will become near inaudible (although I don't know how quiet the Gelid cooler with that particular card will be). 1TB 2.5" drives are readily available, Seagate makes an external 1.5TB 2.5" external drive and Western Digital has a 2TB version. 2.5" drives are more expensive than 3.5" drives but much quieter when seeking. My next boot drive will be a 2.5" 1TB disc.
With a Z77 board you can use the small SSD for caching only, install everything on the larger hard drive, have the SSD cache access and you have both size and speed, it's called Intel Smart Response
. I'll get a SSD for caching soon.