Chosen Solution
I bought a used 2015 iMac with a cracked screen, I installed a 6700k CPU, a blade SSD and SATA HDD with the OWC in-line temp sensor. I de-lidded the CPU and used thermal pads for the GPU, and upon reassembling, it didn’t boot, with no chime and only LED 1&2 lit up. I tried disconnecting both storage drives, put in the original CPU back in, changed RAM and even a different power supply. At some point it regressed to only have #1 LED light up. The heat sink has a stripped screw, so it doesn’t clamp properly. I’m trying to figure out if i somehow killed the logic board, or if it’s the mounting of the heatsink. Or maybe I’m missing something else? Update: I used a different heat sink and we’re back to 1 & 2 LED’s lit. I forgot to mention it turns on, spinning the hdd and fan, and when I try to turn it off, it just turns itself back on.
Pop the CPU out again and inspect the socket pins, a common issue is bending/shorting the pins and/or not properly setting the CPU correctly into the socket as the spring and the RAM shell make it hard. For now stick with the original CPU. Post some good clear pics so we can see things Adding images to an existing question
