PC133 for sunblade 100

Greetings,
I was in the mood of upgrading my sunblade100 in my bedroom, since I recuperated some RAM from intel servers, and found myself with what seems to not work (I was hoping to pass from 256Mb to 2GB... and then upgrading to solaris 10...)
after this failure I tried with just one 512 MB, then one 256MB, then one 128... with no success.
I found on the forum this thread:

If I look at my original 256MB ram and compare with the other 256 MB ram, I notice no difference same brand (?) both have mention:
256MB, SYNCH, 133MHz, CL3, ECC
they differ here:
my SUN:
PC133U-333-542-A
the other:
PC133R-333-542-B1
Any hope?

Thanks

---------- Post updated at 19:55 ---------- Previous update was at 19:19 ----------

I realize the difference is between "unbuffered" and "Registered" is there a workaround?

nope. not as far as i know.

I got my 2GB working after reading the service and other related manuals, and more investigation on google...