Chosen Solution
When there is no ram I get the no ram beeping error, when I insert the ram it doesn’t do anything, opening it up the cpu fan tries to spin but won’t go on for more than 3 secs 1st led is always on and 2nd led lights up for a second or so, 3rd and 4th don’t turn on. I tried a lot of things, no ram, 1 stick of ram, removing and reseating logic board and PSU.
Most likely your power supply has gone bad. That would answer why you don’t get POST tones when you try to start up. Your diagnostic LEDS are probably only showing #1 lit. It may not even light. iMac Intel 27" EMC 2429 Power Supply Replacement
Well I’ve got some bad news for you Apple won’t fix your system so forget going to the Apple Store (your system is on the Vintage-Obsolete list).
Instead try one of their authorized service centers or try an independent Apple repair person,
