They are powerful cards, just make sure you do something for the VRM and other cooling components. Some ppl say the G10 doesn't do enough for those and I think either Linus or another youtuber did a video where they had a 290x on a G10. Look for it.
You may want heatsinks for the VRMs but you dont need those either. NXZT even say so themselves.
Mine run at around 80 on my R9 290X after several hours of BF4 with my Kraken G10.
Gelid do a kit but you could pretty much make your own with a Dremel and some regular heatsinks if you wanted to. I bought the Gelid kit but have yet to fit it.