Compatibility is more suited to matching RAM to motherboard. For example, if oyur RAM increments in 100s while your system increments in x33s, then you will most likely run into issues as you'll need an exact timing map for matching those together. I ran into something similar with my matched pair of OCZ ReaperX Hyper RAM, which are PC28500 (1000 MHz) whereas my mobo likes increments of x33, instead, so matching the OC on my CPU to a value that is compatible with the RAM without overclocknig the RAM too much became an issue for me. I had to settle for a very weird timing ration (that eventually I fine tuned by downstepping the OC on my CPU) so that now the RAM is running at stock 1000 and the CPU is running at stock 1400 so the match comes out to a weird 5:7 ratio, IIRC (Can't exactly boot into the BIOS while typing this to verify lol).
If you had had a matched set of PC25200 you may still have had issues as it simply was not compatible with your mobo (and rightfully so, as if it came with PC23200, then its timings would probably be limited to 400/800.
Yes,yes, yes, I know DDR / DDR2 / DDR3 is supposed to downclock appropriately - but cheaper, higher speed RAM sometimes just doesn't do it.