iMac Late 2005 G5 20" RAM Upgrade Guide (PowerMac12,1) Rod Bland September 18, 2019 03:47 Updated Follow Use this guide to upgrade the RAM in your 2005 17" G5 iMac to a maximum of 2.5GB (2GB x1 plus 512MB onboard RAM) Tools Phillips #1 Screwdriver Anti-static wrist strap Medium Anti-static mat Parts 2GB RAM Module