Had very little sleep last night as my Mac Pro wouldn't start up on switching start up drives. Blinking white light. Never seen this before. Wouldn't even allow the keyboard to work so I couldn't reset PRAM, or make it a target disk. Open up and saw red flashing coming from RAM slot bay area. After a lot of swapping out the 4x 4GB RAM modules I isolated that TWO of the modules were not working. Surprised, as I only expected one bad one. But not two! Anyway, pretty sure these are covered under Ramcity's lifetime warranty. Will contact them to get these returned for replacements. Hopefully no issues with them.. Anyone else had 2x modules die on their Mac Pro, do they often die in pairs?