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20" imac g5 2.1 Ghz With isight Wish to replace 1 gb ddr2 sdram with 2 gb

This should be your machine: Apple iMac G5/2.1 20-Inch (iSight) Specs Identifiers: iSight - MA064LL/A - PowerMac12,1 - A1145 - 2082 RAM Type: PC2-4200 DDR2 Min. RAM Speed: 533 MHz Details: Supports 533 MHz PC2-4200 DDR2 SDRAM. Standard RAM: 512 MB Maximum RAM: 2.5 GB Motherboard RAM: 512 MB RAM Slots: 1 So just add one PC2-4200 DDR stick in the lot. Here’s the guide on doing it: iMac G5 20" Model A1145 RAM Replacement

Where do I “add” it, there is only one slot!