Red CPU LED Light after CPU Upgrade

[rhym1n]

Asus Z170-E Mobo
Intel i7 7700k CPU
(Intel i5 6500 old CPU)

First, we updated the BIOS to version 3504 as ASUS' site says the mobo supports the CPU with this. I believe the BIOS was 1801 before. The i5 continued to work fine for a couple days until the i7 was purchased.

After installing the new CPU, the CPU LED light is stuck on constant red, and nothing displays. It won't even get to POST. You can also see the hardware reboot once after about 20 seconds. We also put the old CPU in, and it does the same thing.

We have tried:
-1 stick of ram in multiple slots on mobo (multiple sticks)
-reseated everything (power cables from psu to mobo, cards, ram, cpu, etc.)
-used proper thermal paste removal and application for i5 and i7
-clearing CMOS, even tried a new CMOS battery
-tried shorting CTRS
-onboard video to rule out GPU
-we are careful with ESD

 

[InvalidError]

Have you triple-checked that you haven't bent pins in the CPU socket? Assuming you are telling the truth about being careful with ESD and re-seating everything properly, bending CPU pins would be the main thing that could still go wrong. Another would be accidentally over-bending the motherboard during the CPU swapping process.

 

[Bob125484]

Here is a link to Asus Z170-E bios. I don't see any bios version 3504 you are referring. It should be version 3007 for 7700K. Are you sure you download and update the right bios version?

https://www.asus.com/us/Motherboards/Z170-E/HelpDesk_CPU/

 

[rhym1n]

We didn't use the Windows tool to update the BIOS. Instead we clicked the Driver & Tools tab within the same link you sent, chose Windows 10 64-bit, and click "See All Downloads" under the BIOS. Here you will see the most recent version, 3504, released 2017/08/11.

Also, InvalidError is right, it's bent pins on the mobo. We did not force anything - I made that mistake years ago and am very cautious about putting in CPUs.