Well it all started around 4:30am when I was woken up by my pc doing a reboot cycle. I pulled the power plug out to stop it and put it back in which made carry on doing the same thing. Its a Dell optiplex 755. The diagnostic lights have 1, 3 & 4 lit up which is not in the list of commen errors. I pulled the battery out to clear the cmos, put it back in and rebooted. i got into the bios and reset the time etc... Once it rebooted it showed 3 and 4 lights which is RAM issues. Put in some good RAM but it displayed the same error. Looked on the net but theres not much help. One answer is that it graphic issues but my card works fine. I tested it in my old pc. Only other thing it could be is the motherboard. Pulling all the RAM out now wont even trigger the error of having no RAM installed. Any one here had simalar problems with a Dell Optiplex 755? I dont have a spare hard drive at the moment so cant even setup my old pc.