Chosen Solution
I change the memory, the power supply, the Logic Board and the Processor and change the hard drive just in case, but still one beep every 5 seconds!!!! What can I do? The iMac does not boot, just turn on the fan… I tried SMC reset and other keyboard fixes but the keyboard looks like does not have power. :-(
On the Apple site it tells that there’s no RAM or it’s not supported. It only supports 600 MHz PC3-12800 DDR3 SDRAM SO-DIMMs (204-pin). The RAM might also not be properly seated or the sockets are broken or the slot pattern isn’t like it should be (the way the RAM is in the 4 sockets might not be in the right order) or one or more dimms are defective.
Try disconnecting the Headphone Jack on the mainboard
