I bought some PC800 ECC RDRAM, and installed it in conjunction with my Non ECC RDRAM. My system did not start and returned me with 3 post beeps (RAM failure).

The research I did into this was that PC800 ECC RDRAM was compatible with all Pentium 4's. But for some reason it is not with mine (Gateway Performance 1300). I did find out after the fact that RDRAM is supposed to be run with compatibility modules (clear RAM modules to fill the empty slots), this I never did as I didn't know I had to.

I now have the additional problem that when I removed the ECC RAM and replaced my old Non ECC RAM, they are not working at all now and return the three post beeps (RAM failure).

Could I have burned out anything in my mobo, or anywhere at all, during this exercise, that is causing my old RAM to fail?

RAM stats

Old RAM that did work together:

Samsung PC800 45 RDRAM 64mb/4 Non ECC (x2 - matched pairs thing)
Samsung PC800 40 RDRAM 128mb/4 Non ECC (x2 - matched pairs)

New RAM that has stopped all the other RAM from working:

Samsung PC800 45 RDRAM 256mb/16 ECC (x2 - matched pairs thing)

I can't get any other specs as my PC wont go past those three post beeps.

Please help, as I have a couple of major web design projects and a management course to complete. I was installing more RAM because my newly purchased Adobe Illustrator requires a minimum of 512mb of RAM to run.