Why does my PC not boot anymore (no display but fans and lights work)?

i would say it is either a simple connection problem or you need to update some drivers try f8 at start up start in safe mode use system restore to a time before the problem look for recent updates that are causing the problem and check for mobo and vid card updates also check your hardware and software against this for vista a href="http://www.microsoft.com/windows/compatibility/" rel="nofollow"http://www.microsoft.com/windows/compati…/a check cpu fan carefully when properly installed it should be tight (no wiggle) the problem is probably simple but there are allot of possibilities