a friend's computer that was functioning normally, suddenly refused to start. when the power button is pressed, NOTHING happens the power unit seems to be okay because, the monitor is powered on.(it is connected to the power unit) a tech guy (not very reliable) had examined the system and said the power unit is okay and the CPU has to be replaced. however the price he quoted for a replacement CPU is suspiciosly low. the power button was examined by me, and shorting the two leads in the power button did not make any difference. also, the mother LED was not burning when the cover was removed any helpful suggestions ? my signature does not look like this

oops. i meant motherboard LED my signature does not look like this

The PSU is not powering your monitor. It may be switching the 110 volt plug on the back of the PSU but this is not a valid way to determine the actual power going to the MB. I would try to replace your PSU first. I would also not take any other suggestions from that tech guy.

i do not have a spare PSU at the moment. i would like to know if a bad CPU can cause a situation like this my signature does not look like this

If you're not getting any of the indicator LEDs lighting up, it's very unlikely that it's a bad CPU. A replacement PSU (power supply unit) will probably run you less than a replacement CPU, and if it turns out the original wan't bad, you can always keep it around as a spare. You might also check first if a cooling fan has become disconnected from power, or is frozen up (was the PC making any noise?). Some mobos refuse to power up if the cooling fan(s) aren't turning. While you're in there, carefully vacuum out (or blow out) all the accumulated dust, but don't touch the boards with the nozzle.

i'll try it out my signature does not look like this