OK this started with buying an Optiarc Sata DVD drive that didn't work after sending the second drive back for a refund I was puzzled to find that the supplier found no fault with it?? But No Prob got the refund and had a Poineer DVR 218l on order, along with a Samsung for the wife's new build, neather would work in my machine when they arrived though, and after giving up put the wife's machine together to find they both worked perfectly So the problem Narrowed down to my Machine, while booting the Drive worked but as soon as windows loaded ether from DVD or HDD the DVD drive stopped working and the system Froze By chance after resetting the cmos I missed the Bios screen (Kids) and smack me in the face the DVD loaded Windows of the Disk and was quite happy to install So Joy yipee when it rebooted during the install went into the Bios and OC'd the CPU again, and the DVD drive stopped working and the system locked up again So Re-Boot and load the optimized defaults and all worked again, so this is obviously being caused through something changing with the Over Clock <_< So CPU Frequency 242 with a 12.5 Multiplier DRAM Voltages 2V everything else set to Auto so all the Auto setting set to Manual one at a time, and the problem tracked down to being the Advanced Chipset Options, DRAM settings K8 <--> NB HT Speed available options are 1X, 2X, 3X, 4X, 5X and Auto set to 4X DVD Drive works, set to 5X the DVD drive locks up the system should anything try to access it. So My question here is are there any smarty pants here that can tell me how to get back to 5X and keep things working, or should I just accept that I'm stuck with 4X? P.S. it took three days and a lot of thinking and trial and error to get this far.