Hello! im having trouble with my compaq dc5850.
It's saying sometimes that date is not set to correct date and need to replace on board battery.
So ive replace the battery also ive reset cmos by restoring bios setting.
That problem is everytime i shut it down it automatically turn on again for no reason at all.
But when I put the back the old cmos its works fine just need to set time again but AFTER a week or few days
problem appears again 
Also before the error appears the pc counts the MBs of the ram
Im using
HP compaq dc5850 Microtower
AMD phenom(tm) 2.3Ghz
4gb ram
BIOS Version/Date Hewlett-Packard 786F6 v01.09, 4/9/2008