If you enjoy quiet, avoid the h100i GTX which us as loud as granny's 1950s vacuum cleaner
It gets it's tail kicked (7C) by the H220-X and the
H100i is 12 times louder
The H220-X is also not CLC but an assemblage of custom loop components, pre-assembled and delivered in a box
-It uses copper rads, H100i is cheaper aluminum
-The use of the copper block / aluminum rad is a HUGE water cooling no no. Never mix metals in a water loop. H220-X is all copper
https://martinsliquidlab.wordpress.com/2012/01/24/corrosion-explored/
-The H220-X has a reservoir, H100i doesn't
-You can add a water block or anything else to the H220-X
The H220-X fits in the 500R and the Enthoo Pro / ProM.... the Pro also fits the H240-X which is even better. The Enthoo ProM fits your budget and fits any liquid cooler with up to a 120mm x 360 or 140 x 280mm radiator
The ProM is slightly smaller version of the Pro
Fits large - Graphic card too
420 mm (16.54 in) No HDD brackets
300 mm (11.8 in) HDD brackets installed
http://phanteks.com/Enthoo-Pro-M.html
http://www.hardwarecanucks.com/news/cases-power-cooling/phanteks-enthoo-pro-m-high-end-features-just-79/
https://www.youtube.com/watch?v=zheXtXgpCUg
"case to beat in this price category"
Water cooled build Mid tower case (w/ Corsair H series cooler installed) for £52.12
http://uk.pcpartpicker.com/part/phanteks-case-phes515pbk
https://www.youtube.com/watch?v=CS8qUvhetV4
You can actually install two H100I GTX in there ... but again I'd use the much better performing H240-X or even the EK Predator 360, both of which will allow you to add a water block for your 970 (or even a 980 Ti) and connect it to the water cooling system.