Hi MCT & prathapml, I o/c my pc about 1 1/2 yrs ago when I bought it. That time my pc was running 2600 o/c. (CPU is AMD TB 2200) 512m x 1 twinmos ram. Gradually I feel that my pc's resources are being ate up by the applications. Especially playing games I can see the game actually take some time to load and not run smoothly. Therefore, I decided to upgrade the ram to 1G. Then Geil ram was coming to the pic and I bougth an ultra ver. PC400 512 x 2, to make good use of dual channel. The performance shall one great step improve, to all. But due to the FBS is different,(cpu=166, Geil memory=200Mhz)I try to set them @ same FBS. From that onwards, I got a couples of freeze, load 1/2way and didn't succefully load to windows. Last nite, I played the setting again. Couple hours late, one of the cold boot, BANG! I got an error message "ntoskrnl.exe is missing" and it couldn't boot. I just don't understand why setting the hardwares and will corrupt the os.