I maintain a tool that reports errors on Linux systems with ECC memory, and also a website describing the tool (http://mcelog.org). I wrote about patterns in the access logs correlated to time some time ago in my blog:
Cosmic ray showers [1] potentially. My prediction is that there should be "clusters" of bit errors every few minutes or so (given sufficient amount of servers...).
I was talking to a sysadmin at a local company running a few thousand servers about getting their ECC error logs in order to look for these, but scraping them apparently wasn't trivially managable for them.