How to test pc? wont start up?

http://www.tomshardware.com/forum/261145-31-perform-ste...

hanz start with the simple check list on the build. make sure you use the bass standoffs and that you did not screw the mb down to the mb tray so it shorting out. also check that the case metal shield on the back of the mb none of the fingers are shortening the mb out. make sure the 4/8 pin pci power cable is connected. most time it on the edge or close to the cpu.
depending where you live and your power supply check that the red 110/220 red switch is set for the right input voltage if your ps has one. in the us it 110v. also check that the power switch on the ps is turned on. a lot of new mb have power good led if the power supply is good the green power good led should be on and not blinking. also a lot of mb have debug led.see if any of them a lit when you turn the mb on. if there a dead short most mb/ps will only power up for a sec..you may see case fan twitch.
other things that will cause system not to post is the cmos battery is misisng or fell off the mb. same for the clear cmos jumper if it on the wrong pins or is missing. a lot of times too you can plug the case wire into the wrong pins and cause the mb to be stuck in reset mode. also check to see that the on button and reset button cables are fine and if there connected to a small case board there connected on the other end. I had builds where the on switch was connected to nothing. the case venor forgot to put a wire from a daughter board to the on switch. sometime some mb bios are old. sometime you may need to use one ram stick and onboard video for the first two or the posts intill you update the bios. may want to try one stick of ram and onboard video.