Power supply must be 350w or higher for the QUAD with G33M03.  WINDOWS HAL is now wrong so windows needs reinstall.  Faster CPU requires 6400 Ram not 5300 Ram. BIos should be updated to latest with OLD CPU.  Systems: Dell Vostro 400: bios 1.0.15[URL]   Fixes/Enhancements:1. Updated Intel microcode.     [URL] [URL] [URL] 350W Power Supply for Inspiron 530 531 Vostro 400 Studio 540 XPS 8000 8100 J130T J515T J517T K159T K660T     
I upgraded this old machine with and SSD drive, and up to 7 GB RAM (8 GB won't start), working with a Core 2 Duo E6750 and latest BIOS available 1.0.15. My motherboard is the DG33M03 model. Installed win10 64 bits and Ubuntu Linux 20, both working OK. I Bought a used Quad Core Q9550, when installed, Win 10 won't boot, even the usb bootable installer won't boot either. Ubuntu is working fine with the Quad Core. Changing back to the original chipset, win10 boots fine. Any suggestions on how to make win 10 work with the Quad Core? I know is an old machine, but for simple desktop usage is more than fine.   Best Regards
Vostro 400, win10 64 bits won't start with new cpu quad core Q9550