We've published a few papers about this that studied (among other things) the effect of temperature on DRAM and hard-drive failure rates. We watch our machines pretty closely. If you're a data geek, Google's a fun place to be.

Disk Study: http://research.google.com/archive/disk_failures.pdf

DRAM Study: http://www.cs.toronto.edu/~bianca/papers/sigmetrics09.pdf