upgrade help needed

I recently bought an old g4 500 mhz sawtooth that had been upgraded with a 1.2 ghz Sonnet processor. I put the processor in my g4 533 Digital Audio. The only thing is that the heatsink that came with the Sonnet Processor overlapped one of my slots for RAM. The Digital Audio only has 3 slots (but for some reason when you go to the System Profiler it say that slot 4 is empty???) and I would rather not have to buy two 512's to max it out. So I used the old heat sink from the original 533 processor for the 1.2 ghz. They were of comparable size only on the 533 heatsink the aluminum "fingers" (I don't know what else to call them) extended all the way from one end to the other, whereas on the 1.2 heatsink they trailed off about hald way down. I would think that having the "fingers" all the way down would disperse heat better. Am I wrong on this? Do you think my processor will overheat after too long using a heatsink not designed for the processor?

Also, on another note ... I thought that PC 100 RAM would work on a PC 133 slot, but a PC 133 would not work on a PC 100's slot. Apparently I was wrong on thise because I was able to procure two 512 PC 100 RAM chips for the only two open slots I have, but when I installed them my g4 gave me some sort of burt and woudn't boot. I stuck a 256 PC 133 in with the other 512 PC 100 and when I boote and went to the Profiler, it wasn't reading the 512. I know it all has to do with the bus speed, but I could have sworn that I have used a 256 PC100 on my 533 before. hhmmm. maybe not.

anyhow, any help would be greatly appreciated.