Hi My previous posting was to unlock my Semp 140. Since then I have picked up a phenom II x2 550 Black Box. I'm trying to unlock it using my Gigabyte GA 785GM-US2H board, bios ver. F4. It's a new build, using 4gb OCZ DDR2 6400. My question / problem is booting into windows. I put in hybrid mode, ACC on, turned off QnC, raised voltage anywhere from 14v to 15v and tried all in between. It posts as a B50 x4 (good) and gets to the windows splash screen (also good) but the splash stays on for anywhere from 1/2 sec to 6 seconds then blank black screen. If I hit reset it will restart and I start all over. This is a new build machine with a fresh intall of XP Pro loaded only with SP1. I'm planning on grabbing SP3 tonight. Is it possible at all that my problem lies with XP as it's only up to date w/ SP1? Would the opperating system keep it from booting as a quad or would it make no difference? Does this sound indicative of defective core? I'm not ready to give up, but I know it a coin flip as to whether it will or won't unlock. I have read the long thread on this forum with everyone's results. It boots no prob as a x2. Also, any other possibilities? Thanks for help!