I'm helping my friend build his first computer. We set it up, and it worked. Then, we clocked the CPU speed at 1.3gHz (should have been ~1.9gHz). We emailed the vendors about the problem and they sent us some procedures to try to get the CPU working better than what it should. We took off the heat sync, to look at the CPU and made sure they sent us the right one (it was mailed in a clear, unpackaged case). It turns out that the CPU was the right model, so we put everything back together and turned it on. One light in the front turned on, but nothing else seemed to get power, the monitor didn't display anything, and it didn't even sound like it was doing anything. Beforehand, we had taken some of the steps the vendor said, we switched some of the jumpers on the board to set some frequency to 133mHz. We set the jumpers back, and still nothing seemed to happen. Does anyone know what in hell happened? We're starting to get irritated with the computer. Any suggestions? (I hope we don't have to get another CPU)

Did you reconnect the cpu fan cable to the motherboard corectly as you took it of because some motherboards wont allow bootup if this is no connected correctly

it could be that the HS was not put back on correctly and it is detecting an overheat condition. it could be that when you put back the HS you didn't have the CPU seated correctly. DId you remove the CPU at any time? Did you re-apply termal paste? Is the paste aluminium based? (The aluminium could get on etches and short out circuits). Did you have to remove any cables to be able to remove the CPU? Did you pull out the power cord and hit the power button (it should blink as it discharges the caps) before you touched the CPU? When you push the power button, does the Power Supply fan turn? Does the CPU fan twitch? If the CPU fan twitches, it's probably the CPU. If the Power Supply fan twitches, you have a short somewhere. If the PS fan doesn't twitch, it's in the power supply. Try a different cord and outlet. otherwise you may have cooked the PS or the CPU. Do you have 133MHz memory? If not, and it was overclocked, it could have fried the ram. a shorted ram may short the power supply.

try to reset the como's or take the power cord out of your computer and take the battier on the mother board out and let you computer sit for like 5 minutes with no power.

What motherboard are you using.