The 4Mb X 1 chips are better. It does not matter if its 8 or 9 chips, in the case of the 9th chip is a SIMM with Parity and is basically ignored by the SE/30. The other "hi-density" SIMMs are hit or miss on the Mac II series, including the SE/30. So some will work for them, others wont.

Also, you should check with a multi-meter to see if all your addresses on the RAM SIMMs are intact. A dead address pin will stop the SE/30 from recognizing RAM at a certain point.