I've been running lots of benchmarks in the lab for work. Well, recently I produced some completely erroneous data. Lots of variation with outliers in the +/-50% range. Just ridiculous. So I'm going through my list of Thing Which Changed: processor, board, disk image, whatever, and I can't figure out what's going wrong. The more I look at the scores I'm generating, the more I think, "Gee, it's like there's some kind of other thread running at the same time, sucking up half the damn CPU."
Sure enough, when I go check, Intel's damn thermal throttling monitor has gone apeshit on me and is sucking down half my resources when it's supposed to be using approximately zero percent. I haven't completed verified that this is the reason, but the odds are good. I just wish the goods weren't quite so odd.
Lord knows how long this stupid thing has been doing this to me, screwing up my measurements. Turns out it also interferes with collecting performance counter statistics. Glad nobody told me.
Now I feel a whole lot less incompetent for being unable to produce really tight data the past two months and a whole lot more screwed over.