The RYK has the smaller chassis size, but you are limited to the M.2 storage. The RYH has the larger (taller) chassis size, but provides for expanded storage via a HDD/SSHD. Which you choose is entirely dependent upon your intended usage and (future) storage needs. Of course, you can always add storage - in either case - via an external USB 3.0 drive.
If you go for the RYH, I might suggest you go for one of Seagate's SSHD models instead; it's typically not that much more expensive (at least here in the U.S.) and there's a reasonable performance gain...
I'd go for RYH (this is what I have), Samsung SM951 and a decent 7200 rpm laptop drive. Not sure whether the hdd/ssd hybrid still has the issue of slowing down over long period of usage.. But for that specs? Light to medium gaming? Work? Mine is used for htpc and light to medium gaming. Samsung SM951 is one of my wish list items.
Thanks, I think 5i5RYH would be better for me cos theres no point on using slim 5i5RYK if upgrade to silent Abel B2 chassis.
I changed my mind about getting 5i7RYHR only cos its runs too loud/hot, but looks like www.quietpc.com sell current NUCs with quite cooler.(they named it UltraNUC Pro)
Unfortunately doesn't look like they sell the NUC cooler by itself, and UltraNUC Pro seems very overpriced just cos they upgrade the cooler. (~$210 extra, 1 week for delivery, only 2 years warranty etc).
Might just buy MSI Cubi or Asus VivoMini instead cos they are suppose to run quiet unlike Intel NUC.