Hey everyone, I recently took shipment of my BTO iMac and upgraded the RAM with Kingston HyperX pnp 1600mhz DDR3 RAM 1.5v. Everything was fine for around 2 hours and then all of a sudden, my machine shut down and I got a Kernel Panic. Booted back up, same thing shortly after. Three Kernel panics by the end of the first day (on a brand new machine :-S) Second day, same thing. Contacted Apple support who said put the Apple RAM back in, test and see if it works. He did say that the documentation would suggest that this RAM is absolutely fine to use (1.5v) and the specifcation and product wiring diagrams do not suggest that it is 1.35v only. Switched back to the Apple RAM... no Kernel Panics! Sending the RAM back to Amazon tomorrow as i'm guessing one of the sticks must be defective, but interesting that Apple rep confirmed it is ok to use. Asked for a refund as I have since heard some Kingston's RAM can be unreliable and don't want to chance it again. Any recommendations on brands?