I'm running my memories at 140 MHz, CAS 3, and they're all PC100. I had one stick that barely made 115, but 3 out of 4 is not too bad. The system is completely stable (but I wouldn't clock this high if I had very important work on it, of course). The sticks are:
·One Micron 32 MB PC125 (inofficial marking)
·Two noname 64 MB PC100.
Addition: the 815 boards in general might be a little bit more sensitive to out-of-spec signals from the DIMMs, I understand. But you can always try...
🙂