The PSU I received in my PC was 600w's by Thermal Lake. You will more than likely get something different because each PC isn't built using the same brand of parts. For example: some may get a ZOTAC GTX 1080 and others may get an EVGA GTX 1080-- it really depends. As far as water cooling, I looked into this personally because I wanted to water-cool the 1600X because of the fear that it may get super hot, but I was advised that even overclocking the 1600X that a water-cooler isn't necessary, but that isn't me telling you not to use one. Water coolers like the Corsair Hydro Series and I believe the NZXT Kraken and Artic Liquid will fit. So, yes, the case has enough space for what you want to add.