Probably something with 2 120mm fans - 1 for intake and 1 for exhaust. The reference 260's don't get ultra hot so any mid-size or full case should do with good cable management. it will also depend on the 260 that you get. The reference design outputs heat from the rear through a 'closed' system but there are other vendors that may sell one with a localized cooling solution with larger heatsinks. These are usually cooler designs but in effect may heat up your case a bit more.