This is a guess, and should not be taken as anything more.
MCLCK refers to the sytem clock of Mater CLock
THe machine was/is clocked at 166 MHz. It migth have been modified / overclocked at a higher speed.
Memorry was added. The added memory is Double Datta Rate (DDR) running at ahigher spped than the bus can accomodate.
NTSC usually means National TelevisionSystem Comittee ( for info see http://www.ntsc-tv.com )which makes me think of diplay adapaters.
Since this is happening before the BIOS POST, it's probably something leading to that.
So, putting these things together, I'd guess that there's an incompatiblity between some of your system components that are not operating at the clock speed intended. SOme guesses:
-Motherboard was tweaked to be overclocked.
-Memory was added, probably DDR, that is not operating at the "double" rate.
-Display adapter had a jumper changed
Just guesses, but perhaps..... one never knows.