We now have a donation of an ASUS VX97 motherboard but it has no cpu. The downloaded manual lists as supported Intel Pentium 75-233; (P55C-MMX), (P54C/P54CS) IBM Cyrix 6 x 86 (Rev 2.7 or later) IBM Cyrix 6 x 86 MX; AMD K6 PR166-PR233. Which of these would you recommend we look for and retailers for out of date cpus? thanks for any input