DELL T7810 CPU Upgrade

Hi, first sorry for my english I am native german, hope you will understand me.

I have a DELL T7810 Workstation since 2017 with two E5-2643v4 and I am very satified, but it could have more CPU power after 8 Years.

Therefor I got two E5-2696v4 (22c/44T) and put them into the T7810. Anyhow it seems that the BIOS hs some problems with the CPUs.

After installing the CPUs I cleared the BIOS and I was able to set the BIOS parameters as I wished. Then reboot.

I got the following error messages: "Get FW Version Error" followed by "(A7) Me FW Downgrade - Request MeSpiLock Failed" followed by "Error sending End Of Post message to ME !".

Afterwards it is booting normally to Win11. But I can't access the BIOS once again without clearing it first. The PC will freeze after the DELL BIOS Logo with only a "_" at the top left of the screen. Update: it is not freezing, but it takes ~5min to get to the BIOS screen.

Additionally the boot process will take 5min because of the error messages.

In Windows everythis is fine. I have all 44 cores/88threads, the Benchmarks are as expected.

Is it possible that this processor is not supported by the T7810?

Because https://www.dell.com/community/en/conversations/precision-fixed-workstations/dell-t7810-w28-core-and-2x-e5-2680v4-128gb-memory-suggestions-on-processor-upgrades/647fa101f4ccf8a8de62a808 it is written that all E5-26xx should work.

Is there any way to get it tp work/boot faster? Because the CPU power is quite good, see conebench R24: