To further what captaincranky has said, one of my PC's with a 4870 would idle around 75-78C with the fan at low speed. The 4000 series seems to choose higher idle temps over fan noise.
It wasn't until I got a videocard BIOS tool to adjust the fan curve myself that I was able to get my 4870 to idle under 50C, and that was by programming my own temp/fan curve and burn that new BIOS into the card (not recommended to novices).
Stock, a 4000-series will be fine, just it will run fairly hot at idle and is very lenient on bumping up the fan speed to keep things quiet. You can always override the fan speed in the CCC manually, but then that is a static fan speed that doesn't adjust based on temp (which the 4000-series will do as it gets hotter).
Overall though, a 4000-series will keep the temp under any damaging level, which is what is truly important. They just choose a higher temp to fan ratio to adjust to fan-noise complaints.