right now it is available to upgrade G4 towers or cumes with 1.7 ghz, therfore the 1.5 ghz barrier is broken, hence new powerbooks will run at 1.7 ghz Processor upgrade G4 @ 1.7 GHz - Lionel - 10:37:11 Source : Macgeneration Sonnet has just released a new model for its processor upgrade card for PowerMac G4 AGP: ENCORE/ST G4 1.7GHz! This processor upgrade can be installed in the following PMG4 models: - Power Mac G4 (AGP Graphics) - Power Mac G4 (Gigabit Ethernet) - Power Mac G4 (Digital Audio) - Power Mac G4 (QuickSilver 2001) - Power Mac G4 (QuickSilver 2002 with single processor) - Power Mac G4 Cube (specific models SG4-C1200 and SG4-C1700 running respectively @ 1.2 or 1.7GHz) - Macintosh Server G4 (Equivalent to listed Power Mac G4 models) (So all PMG4 AGP SDR bus and Cube, not for PMG4 MDD). There is no information regarding the 1.7GHz G4. The PDF TechNote is providing information for STG4 up to 1.4GHz, based on PPC 745X featuring 256kB L2 cache and 2MB L3 cache. One can expect that the 1.7GHz model will be based on a 7447, with 512 L2 cache and no L3 cache. It could be interesting to compare performance of cards with and without L3 cache. For the cube, the processor upgrade card is including a quiet fan, and Sonnet recommends professional installation Price for the STG4 1.7GHz: 499.95$.