Sonnet has designed the Crescendo/7200 to utilize the same memory DIMMs that are used to upgrade the motherboard RAM in these popular Power Macintosh models. Sonnet recommends Fast Page Mode (FPM); 60 ns; 5 volt; 4K refresh; 168-pin DIMMs.
Compatible DIMMs are also available through most of Sonnet's wide channel of knowledgeable resellers.
Some 128MB DIMMs that employ an 8K refresh are known to pose potential problems. 128MB DIMMs are typically composed of 16 chips, each a 16Mx4 part. There are two types that are used, the "4K Refresh" and the "8K Refresh". The Crescendo/7200 is not compatible with some DIMMs made with "8K Refresh" parts because the timing margins are so thin that the electrical "noise" generated by the card causes errors. The "8K" versus "4K" parts can be identified by the part numbers of the chips on the DIMM, or by checking with the manufacturer of the chips.