I have a MSI k9n6gm motherboard. It looks like this:
As you can see, the fan's holes aren't really in a square; it's more of a rectangle. After asking a TigerDirect representative, I tried a fan. It didn't fit and I'm going to get a return/refund.
Now they're suggesting this one:
Masscool 5F9001B1H3 CPU Cooling Fan - Socket 939, 940, AM2, AM2+ (I can't post more than one link, it's on TigerDirect)
Since they failed me once, I want to investigate on my own this time. How does one find fans that will fit their motherboard?