Chosen Solution
Greetings! Just finished installed the memory maxxer kit (16 Gb) and while in there, swapped out the old 5400 rpm hd for ssd. Also removed a boatload of dust and reapplied thermal paste between heat sink and cpu after cleaning well. On power up got the chime and thought all was well. No logo though! After about 15-10 sec fans went full bore. Still no video! Was trying the shift-option-command-R boot to downgrade mac os to non catalina…any idea what to do next? Thanks! Update (12/16/2020)
here are a few pix…one after cleaning the old paste and my “thin”(?) of the new stuff. Maybe too much? Also, not sure if old paste residue along the edges is potentially a problem Thanks again! Update (01/02/2021) This is a update of my second attempt to get this iMac working again.I disassembled everything once again and following @danj ‘s advice, removed my first round of thermal compound plus the residual from the initial install when the machine was mfg’d.
I did use the CRC QD Contact cleaner and it worked well! I tilted the logic board, built a “catch-pan” of sorts with a rolled up paper towel and within two or three one-second sprays, obtained a clean CPU and heat sink, including the old paste that I was unable to remove in my first attempt.
Used the following amount of thermal paste on reassembly and checked to not overflow this time…
Reassembled it and it now runs like a rocket, probably faster than when new (now using SSD with 16 Gb RAM rather than the original build with a mechanical hard drive and only 8 Gb.)!!! Thanks for the help Dan! Next project (soon, I hope) is cleaning out dust from my mid 2011 27” iMac while upgrading CPU and video card using a pull from eBay…
Time to back wind! Take the RAM out putting back the original RAM and the HDD. What happened then? I’m suspecting you have an issue with the CPU/GPU work you did.
