HELP! Dual processors not seen. What happened to them?

I have a twofold problem, both on AGP Graphics machines with the Sawtooth boards. I purchased mine used about a year ago and it came with a dual 550 processor upgrade installed. It works great, but somewhere recently, maybe after my latest upgrade (10.4.8) I checked my system profiler and it now shows the processors as dual 500s. It used to say dual 550. Any idea where the other 50s went? Could this be a glitch in the OS that doesn't allow it to see the the extra gHz? I may try zapping the PRAM, but do you think it's because of the software? I'm baffled. The other part of my problem is I just upgraded the other AGP machine with a dual 500 from a gigabit ethernet unit. It showed up fine as a dual 500 in the profiler. Then I swapped in a 160 gig internal and popped the OS on it and relegated the smaller, second internal into a storage drive, erasing the OS on that one. After doing that, it just shows up in the profiler as a single 500. Weird. I've never heard of a dual processor losing half and still work fine on the other. As I said before, it was showing up fine until I installed Tiger on the new drive, transfered the info from the previous system via the installer, and now, only one processor shows. Any ideas or suggestions for both machines? Particularly the one missing the entire half of the processor? Thanks!

G4 Dual 550 Mac OS X (10.4.8) 1.2 GB RAM, 380 GB Storage, DVD Burner/Handy Slide-Out Cup Holder, USB2, TV Tune