i am currently operating on an early 2008 Mac Pro with: 2 x 2.8 GHz Quad-Core Intel Xeon 4GB DDR2 PC6400 RAM I have been operating Logic 9.1 in 32-bit and OS 10.6.8 in 32-bit as well. (the 32-bit thing was something I only discovered last night - I didn't realize you had to set 64-bit manually on the early 2008 Mac Pros. so I've been operating this way for 3 years since I bought this machine used.) Last night I was operating a session with 24 stereo tracks all using Play, EXS24 and Kontakt. Big orchestral software instruments. For the first time my session started freezing and it appeared I'd finally hit the ceiling. I could then not open any other session because I got a "session closing due to lack of memory". I somehow realized my computer was running in 32-bit, used the Terminal login to permanently enable 64-bit startup, set Logic to run in 64-bit and now all sessions work again. However: I WOULD like to update my RAM from 4GB to maximize performance on 64-bit, since realistically I am not really doing anything with that 64-bit capability other than preventing crashes. Now, it lets me close or disable a track if there's low memory, instead of shutting down entirely. I am currently operating with 4 empty slots and 1x1GB in the first 4. Would it be screwy to have the first 4 slots be regular 1x1GB and the next 2 be extreme performance RAM ? I was thinking the "gaming" ram (2x4GB). Any advice is most appreciated.