27" late 2015 imac won't start after upgrades

[strebor71]

Installed a new blade drive, ssd and i7 6700 cpu. now no nothing from power button press. I checked diagnostic led's and no lights when plugged in to ac power. Did i brick my logic board? any other tests to run??

 

[CooperBox]

You didn't say but I presume it was the i7 6700k you installed? Was it purchased new in box, or from a 'Bay' seller?
I recall reading that several others doing a similar upgrade have had problems. One had a bad experience with an alledged refurbished 6700k which turned out to be bad. Others have bent one or more cpu pins on fitment due to corner pinching when moving the motherboard to fit the heatsink.
When you disassemble again to check for any bent cpu pins, take careful note that all internal cables are correctly located. With luck you may find you have overlooked a connector or one that is not correctly seated.
Pls report back on your findings possibly to assist others.

 

[strebor71]

Thanks for the reply, and yes it is a i7 6700k. and it was purchased used from ebay. everything else is new. I have done exactly what you suggested and looked for bent pins, as that has bit me before on a pc build. I read on one thread that if there were no lights on the diag. led's that meant the logic board was most likely dead but after further reasearch maybe not. a question i have is that lets say that the reason it wont boot is due to a bent cpu pin, or maybe a faulty pcie adapter, shouldnt the diagnostic LED's still work as normal, ie. that the No. 1 LED be on when mains power is plugged in? I would think so. After following the steps in a trouble shoot I found on ifixit it appears that it may very well be the power supply. But I find it very unlikely and would be a crazy coincidence that the power supply decided to die right when i did this upgrade. The two pieces of this upgrade that are the biggest culprits are the used i7 chip and the m.2 blade drive adapter. I guess at this point I will take it back apart and remove the i7 processor put back in the i5 and see if it boots, that is the only used part, if not then ill try taking out the new m.2 drive and adapter. There is about a zero chance that it is the new ssd hard drive so that doesnt even factor in.

 

[strebor71]

just a quick update for others with similar issues:

turns out that it was the new m.2 drive and adapter that was causing the board to not function.
WD_BLACK 1TB SN750 SE NVMe Internal Gaming SSD Solid State Drive - Gen4 PCIe, M.2 2280, Up to 3,600 MB/s - WDS100T1B0E

Sintech NGFF M.2 nVME SSD Adapter Card for Upgrade 2013-2015 Year Macs

as soon as i took it out and applied power the 1&2 LED's lit up. I saw that sometimes the adapter can short out in the slot and putting electrical tape to prevent it, didn't have any effect. don't know if i got a bad adapter or if the m.2 I used isn't compatible or what. which is a bummer cuz I really wanted to boot off that m.2 drive. oh well. got the new i7 6700 4.0Ghz and new 1TB SanDisk SSD installed, as well as 32GB of ram and all is working perfect.

If anyone has any idea of what they think was wrong I'd love to hear it. cuz at this point I got a 1TB m.2 and an adapter card doing nothing. Is it worth getting a thunderbolt 2 enclosure? I also heard that getting a thunderbolt 3 enclosure with a thunderbolt 3 to 2 adapter is much faster. is that true? any suggestions for parts?