I'm slightly concerned about the temperature of a B2 memory module: Ambient: 25C (77F) Mem Module A1: 48C (118.4F) Mem Module A2: 51C (123.8F) Mem Module B1: 52C (125.6F) Mem Module B2: 60C (140.0F) All 4 modules in A1, A2, B1 and B2 are identical Apple 1GB modules. 60C (140F) for B2 is when idling. Under load yesterday it reached 74C (165F), but I suspect it might go higher if really pushed.  Identical in the sense of same speed and capacity. It could be that the added modules were made by a different manufacturer. Oh, and I did just slap the new modules in A2 and B2 without first moving B1 to A2. I figured the move wouldn't be necessary given that they're all 1GB modules. Maybe I reasoned incorrectly.