HP Elitedesk 800 G4 Mini CPU Issues

[James_F]

I'm in the process of adding some small upgrades to my HP Elitedesk 800 G4 Mini, including a USB C daughter board with PD and Display Out and a new CPU, the i7 9700. I am installing it in place of the original i5 8600T. My issue is that after installing it and powering the system on, the power LED flashes red 3 times, then white 5 times, which according to the support documents for the SFF version of the same generation and name, means that the CPU is not detected. The LGA 1151 socket on the 35-watt board I have supports 9th Gen CPUs, so I'm not sure why it's not recognizing the CPU. Also, I have a 95-watt power supply connected, so I know the board is getting enough juice.  The system was running fine before I swapped chips, and I know the highest-end CPU this particular computer was shipped with was the i7 8700, so I'm trying to figure out if the CPU I bought is dead, if I need to install a BIOS update, or if despite the socket supporting the CPU, the motherboard somehow doesn't (PN: L19395-001). Any help or tips are appreciated.

[Paul_Tikkanen]

You would have to show me where you have found that the model series supports the Intel 9th gen core processors.

All of the HP specs I could find indicate the 35W 800 G4 DM models support the i7-8700T at the max.

HP Elite 800 G4 Business Desktop Business PCs

The 800 G5 DM's support the Intel 9th gen core processors.

HP EliteDesk 800 G5 Desktop Mini Business PC Specifications | HP® Support

If your PCs top cover is not vented like the one in my 800 G3 DM 35W model has, installing a higher wattage processor will most likely result in overheating.