iMac 27 2019 processor upgrade problem

[Corben Dallas]

I have iMac 27 2019 i5 8500 which i just upgrade i9 9900k. After upgrade iMac boots with no sound, only two leds lit, second and third. I took processor out few times to ensure everything is ok, but no diffence. I test with other psu and LCD cable and chance motherboard battery but no difference.

Any idea what to do next?

 

[Nguyen Duc Hieu]

I have iMac 27 2019 i5 8500 which i just upgrade i9 9900k. After upgrade iMac boots with no sound, only two leds lit, second and third. I took processor out few times to ensure everything is ok, but no diffence. I test with other psu and LCD cable and chance motherboard battery but no difference.

Any idea what to do next?

Put back the i5 8500 to check if you had screwed up your iMac.

 

[CooperBox]

Good suggestion to reinstall the i5 8500 and see if everything functions as originally.
Two questions.
i) Was the i9 990k purchased new in it's box, or used from an on-line seller? If the latter you wouldn't be the first to have bought a defective CPU.
ii)Whilst reinstalling hardware after your i9 9900k install, did you methodically follow a checklist for refit of all connectors etc, or just go from memory/your intuition which can often lead to the result you describe.

 

[uller6]

Last time something like this happened to me I had forgotten to plug in the speaker cables after putting the machine back together. hopefully it’s an easy fix like this and you didn’t break something during the cpu switch. It’s easy to forget how sensitive motherboards and components are to ESD.

 

[siomitos]

Take out the processor again carefully and check all the pins on the CPU Socket..
I had the same case with late 2015 when i put the 6600K instead of the i5

 

[realeoin]

I'm going to write here because I had the same issue after the CPU upgrade - two LEDs, blank screen, no boot

I had a PC with an z390 1151 socket so I was able to test both CPUs as working perfectly

After a good deal of messing around I realised that it was almost 100% damaged pins on the iMac CPU socket

The heatsink and radiator keep the CPU in place on the Logic Board

The heatsink is such a pain in the ass to remove and put back together that it was likely the pins were damaged in the process