All DDR3 RAM of the same frequency performs almost identical in all tests run by numerous hardware sites such as Tom's, Anand's, etc. so just pick your favorite RAM specified for your Intel CPU from any of the name brands like Corsair, Kingston, Muskin, G.Skill, Patriot, etc. and you'll be fine.
BTW water-cooling is a waste of money as many air cooled HSFs are as good or better than reasonably priced H2O coolers. You can compare performance of the air and H2O coolers at the link below.