Is that the right serial number? Apple's website doesn't recognize it. Anyway, according to these specs, your G4 wasn't available from the factory with dual processors: http://support.apple.com/specs/powermac/Power_Mac_G4_AGP.html That doesn't mean your Mac can't use dual processors from another model, but I don't know. You can certainly use aftermarket dual processors from companies like Sonnet and Powerlogix. http://macsales.com/ is a good place to start looking, though there are other good sources. -- Rich On Nov 8, 2007 7:23 PM, c m <dachamp_11226 at yahoo.com> wrote: > can I upgrade the processor in my G4 APG 400MHz to a > dual processor? > > here is my system profile: > > Machine Name: Power Mac G4 (AGP graphics) > Machine Model: PowerMac3,1 > CPU Type: PowerPC G4 (2.9) > Number Of CPUs: 1 > CPU Speed: 400 MHz > L2 Cache (per CPU): 1 MB > Memory: 1.5 GB > Bus Speed: 100 MHz > Boot ROM Version: 4.2.8f1 > Serial Number: XA0091A2HSE > Sales Order Number: M7641LL/A