Hi all I have the following IMAC G5 bought in 2006. Machine Name: iMac G5 Machine Model: PowerMac12,1 CPU Type: PowerPC G5 (3.1) Number Of CPUs: 1 CPU Speed: 2.1 GHz L2 Cache (per CPU): 512 KB Memory: 512 MB Bus Speed: 700 MHz Boot ROM Version: 5.2.6f1 As you can see, only 512MB of RAM. I bought a 2GB stick of DDR2 PC5300 and had someone at PC World fit it. The IMAC does not seem to be finding the memory, it just shows the built in 512MB. Under system profiler it reads the slot as empty DIMM1/J6700. Anyone got any idea what the problem may be? We have triple checked and the stick is fitted correctly, restarted a few times but no joy.