I understand Dell does not support Windows 10 on the Precision M6400, but I love this machine and a number of people posted that they tried it and it seems to work fine.  I upgraded mine and I agree, initially it seems to be working fine; however, there are a few items in Device Manager that look to be not happy.  There are 3 items called "Base System Device" and one item called "Broadcom USH" that are showing issues.

PCI\VEN_1180&DEV_0852&SUBSYS_02511028&REV_11\4&31182d7c&0&0DF0

PCI\VEN_1180&DEV_0843&SUBSYS_02511028&REV_11\4&31182d7c&0&0BF0

PCI\VEN_1180&DEV_0592&SUBSYS_02511028&REV_11\4&31182d7c&0&0CF0

USB\VID_0A5C&PID_5800&MI_00\6&66de6c9&0&0000

Any help finding drivers for these devices that would be compatible with Windows 10 64-bit would be greatly appreciated.