Take a look at this: [View:en.community.dell.com/.../19501427] If none of it works, you need to replace the motherboard and/or processor(s).
I have a PE 2950 that for some reason, randomly shut down during the day. Ever since that day I have been unable to start it up. Plugging in our server into multiple outlets through out the house. The server shows signs of power on the motherboard and LCD however when the power button is pressed. For a second or so, the server sounds like its turning on then immediately shuts off and the LCD displays "E122C".  I looked about on the forums and found nothing that helps fix this problem. We thought the NVRAM may need clearing but that didn't do us any good. Does anyone know what might be the problem and/or way to fix it?  Thanks, Jorden
PowerEdge 2950 Gen I refuses to power.