Answer to "Diagnostic LEDs OK but no power"im in the same boat. had the logic board and the psu out without any signs of damage. Im tempted to check the PSU power outputs as per this guide iMac Intel 20" EMC 2210 Power Supply Output Voltage Test ive got a DP to vga on order so will see what i get with that. odd thing is i dont get the chime on boot. but the hard drive does spin up.