Shoutbox

High 40s is (depending on the drive type) quite toasty.  Over time, it may shorten the life of your drive.

Ideally,  your case would provide adequate ventilation for the hard drives, preferably a case fan near them.  You probably don't want to buy a new case just for that, but keep that in mind for the next time you have to choose one.

If you have more than one hard drive, avoid installing them stacked directly on top of each other in the 3.5" bays.  In other words, try to not do this:



The setup in that particular picture is not the worst, as the drive cage seems to leave some space between the drives, for air flow.  In some cheap cases, there is often none and that is a recipe for a thermal drive failure.

If your case has locations for case fans, either in front or the rear, which do not have a fan installed, start by getting some case fans.  When it comes to drive coolers, the design I prefer is something like this:



The problem with all drive coolers is that the small fans in them are loud and don't last that long, but if that's what it takes, something like the above is best -- because it blows outside air on the drive and actually helps reduce temperatures inside the case, instead of trying to cool the drive with already warm case air and heating that up some more.