The #1 part to go faulty is the memory controller. Even IBM posted a technical bulletin stating that there was a severe problem with the use of ROHS solder with the chips. If you ever start to see memory issues and intermittent junk like that, DO NOT TOUCH THE RAM OR THE CPU as coming from experience this ALWAYS disturbed the chip enough to cause the BGA joints to completely fail.
From a previous employer, for every 15 G5's we got in per month for recycling, 13 had cold BGA joints and were dead, another would ahve a dead power supply or a leaky LCU and the odd one out would work and those we sold wholesale or if we were feeling dangerous, we blasted them out with compressed air, put a fresh install on them, and sold them AS-IS.
There was a website somewhere that went through the full instructions on how to reflow the memory controller and hopefully fix the problem for the time being. It's a time critical process and you need a fairly good thermometer to get your oven to follow the reflow curve.
From a previous employer, for every 15 G5's we got in per month for recycling, 13 had cold BGA joints and were dead, another would ahve a dead power supply or a leaky LCU and the odd one out would work and those we sold wholesale or if we were feeling dangerous, we blasted them out with compressed air, put a fresh install on them, and sold them AS-IS.
There was a website somewhere that went through the full instructions on how to reflow the memory controller and hopefully fix the problem for the time being. It's a time critical process and you need a fairly good thermometer to get your oven to follow the reflow curve.