In October 2010, I installed a 6GB kit (4+2) from OWC and everything ran very smoothly. I was unaware at the time that a later revision of EFI Firmware Update 1.4 added the ability to successfully address 8GB. I first learned about that update on these boards in February 2011. A few weeks ago, I figured it's finally time to get the upgrade. I checked the page at MacSales to make sure I did in fact have the correct firmware and ordered a 4GB stick with the plan to use it to replace the 2GB in the top slot. From the day I upgraded, about one week ago, I began noticing instability in Safari and other applications, but nothing that crashed the whole computer. For the last 4 days, however, I have had the entire machine either freeze, spontaneously reboot, or show a grey screen of death at least once per day. For the record, I have a 2.0GHz Late-2008 MacBook 5,1, Boot ROM version MB51.007D.B03, SMC version 1.32f8, with one 1067MHz, 4GB stick of OWC RAM in the bottom slot that was purchased in October 2010, and another 1067MHz, 4GB stick of OWC RAM in the top slot that was purchased a little over a week ago. The older stick has a sticker on both sides, while the newer one has a sticker only on the bottom side. Can't imagine that matters, but may as well be thorough. The system ran from October 2010 until last week with the 6GB RAM kit (the older 4GB stick still in the bottom slot, with its companion 1067MHz, 2GB OWC stick in the top slot) with perfect stability in Snow Leopard and Mountain Lion (meaning no system freezes or crashes of any kind). I had nothing remotely resembling stability under any version of Lion, so from July 20, 2011 until July 25 2012, I suffered application instability and dozens and dozens of system freezes and kernel panics. I don't believe those were RAM-related, though. So I'd like to ask whether anyone is successfully using 8GB of RAM in their Late-2008 MacBooks, and whether anyone else has tried but suffered system instability as a result? For those of you who tried but suffered, what did you end up doing? Did you revert to 6GB? Was there some solution you worked out that finally allowed you to use 8GB with stability? Does anyone have any advice?