hey peeeeeople. my mate offloaded this old pc to me. lol. he had no idea if it worked. anyway plugged it in. it didnt. so i tried a different psu. no go. so im just wondering does that mean the mobo is dead? there is no (well there seems to be no) life coming from any thing wen i press the power button. and yes the little power switch buttom is correctly conected to the motherboard. thanks for ur help -locky

What wattage PSU?

im not sure wat the original was cause there looked like a pretty new 500 w psu was in there. i tried a 400 w... if i was to put a higher w psu in than wat was originaly intended would i blow the components?

No, the components will only draw as much power as they need. Both the power supply and the motherboard need to be working to get power up. The motherboard checks the voltages from the power supply and if they are not within tolerance, it won't send a 'power good' signal back to the power supply. Without that signal the power supply will not stay up. Disconnect any drives and pull all the cards to make sure one of them isn't causing a problem.

If you have too much wattage the system won't power on(it can't draw enough power to power on). Run the PSU calculator: http://www.extreme.outervision.com/ Post your system specs if you don't wanna run the calculator and I can probably tell you if your going too big on the PSU.

It doesn't matter if the PS has more capacity than you need. It will start up the computer as long as the PS has at least a minimal load connected to it. Something else is wrong. Ask you mate if he can remember why he stopped using the computer, and what he did just before that. Are you SURE you have the power switch connected to the proper pins? It may not have been connected to the right pins in the first place. If you have a manual for the mboard, such as on the CD that came with the mboard, look at it to make sure - labelling on the mboard can be misleading. If you don't have a manual, get one. Remove the AC power to the case, open up the case. Try moving the cpu fan by turning the blades with your finger or some object. It should move in jumps but be easy to turn. If it is difficult to turn the cpu fan probably cannot spin, and the CPU has overheated and is probably burnt out. If the cpu fan spins ok but the cpu fan and/or it's heatsink is filthy that can also cause the cpu to overheat, but it is less likely the cpu is burnt out. Try the same thing with the power supply you removed - if the fan that was at the back of the case is difficult to turn, the original PS has probably failed. Alternately, sniff the original PS to see if you can detect a definite strong burnt wiring / burnt plasticy kind of smell - if you can the PS has overheated and has probably failed. If the original PS failed, the damage that can do to the mboard or cpu or other components connected to the mboard is unfortunately random. If the original PS is a known good brand and model, it is less likely something other than the PS was damaged, but if it was an el-cheapo, something else is more likely to have been damaged. E.g. If the computer is an emachines system, especially if it has a Bestec PS, the mboard has probably been fried by the failing PS. Someone may have installed ram that is incompatible with the mboard chipset - in the worst cases, the mboard will not boot at all, or even beep, with that ram installed. To check for that, remove all the ram, restore AC power to the case, then try booting. If there is nothing else wrong, the mboard will start up and you will hear a beep pattern that indicates there is no ram installed, if you have a speaker or speakers hooked up properly so that you can hear mboard beeps. Someone may have installed one or more ram modules backwards then tried to boot the computer. To check for that, remove the ram and examine the ram slots using good lighting - look for carbon deposits, and zapped contacts - damaged from melting or ones that are missing altogether.