Came to this group as a result of googling a processor I was investigating and thought it might be a good place to get some help. I will also try to answer question but I don't think I am as tech smart as you guys. Anyway, here is my problem: I have been running a celeron chip for years, in a system that I built. Yes, I had help picking out the processor then too. Can now afford to upgrade to P4 and am confused as to what to get. My motherboard is MSI MS-6728 which is 865PE Neo2 Platinum. The book says it will support P4 Northwood/Prescott Socket 478, up to 3.4 or higher, FSB 400 for Northwood only, 533, 800MHz for Prescott. Well the above sounds easy until you start comparing it to the language on ebay, then I get lost. I have found the following on ebay, cause you can't get this chip in the stores anymore: SL7CH, a 13 micron chip with 1mb L2 cashe and 2mb L3 cashe SL7PP, a 90 micron chip with 1mb L2, no mention of L3; says it is extreme chip SL8K4, a 90 micron chip with 1mb of L2 SL7E6, 90 micro with 1mb L2 I guess my first question is will my pc use either the 13 or 90 micron chip?? Is 1 better than the other? WHY? Could someone advise me by putting these cpus in 1234 order as to what I should attempt to buy and sort of explain why one is better than the other?? I really appreciate your help. Hilltopsurfer.