My first impression and response would be no. But then I've never tried and don't know 100% for sure. My assumption is that Your single 733MHz QS G4 is a single processor system. It's never had a dual processor in it before so the QS may not be able to communicate with the dual 1GHz processor without some sort of Firmware upgrade. But Then there are Upgrade kits sold by a few companies to do upgrade a Single processor G4 to a Dual G4. I do not know what those kits from Power Logix or Sonnett or Newer Technology employs. I suggest you ask around more to other people on this List and also check out other Mac upgrade lists and maybe some retailers such as OWC (www.macsales.com) and see what they tell you. Peace, Luke Rademacher Liquid Zone Graphics Mac mini 2.0Ghz Intel Core 2 Duo, 3GB RAM, 80GB HD, Combo DVD/CDRW, Mac OSX Leopard 10.5.5, ext NewerTech miniStack w/ 320GB HD. MDD Dual 1.25Ghz G4, 2GB RAM, 250GB/120GB/80GB HD's, 16x DL DVD±R/RW Superdrive, Mac OSX Tiger 10.4.11, Classic Mac OS 9.2.2. External 1TB HD FireWire 400 Intel Celeron 2GHz, 1GB RAM, 80GB HD, Ubuntu Linux 8.04 5.5th gen 80GB Enhanced Video iPod Canon CanoScan 8400F Canon Pixma iP4500 On Dec 22, 2008, at 3:21 PM, Alan Kidner wrote: > Can I upgrade my July 2001 Quicksilver G4 (733MHz M8359LL/A) using > an Apple duel 1GHz processor with heatsink and fan from a 2002 > Quicksilver G4? > > Any help much appreciated. Thank you. > _______________________________________________ > G4 mailing list > G4 at listserver.themacintoshguy.com > http://listserver.themacintoshguy.com/mailman/listinfo/g4