After a long research I thought that my current Precision 3660 with Core i7-12700k could be upgraded to Core i9-13900k. However this clearly wasn't the case as immediately after turning the power on, an error comes "Intel 13th gen processor not supported. System will auto-shutdown in 30 seconds."

This sounds to me like an attempt from Dell's side to prohibit CPU upgrades as:

• W680 Chipset supports 13th gen (Intel® W680 Chipset)
• The computer powers on, if 13th gen would really not be supported on HW level, PC wouldn't even POST
• You can now order Precision 3660 with either 12gen or 13gen
• There's no different drivers nor BIOS's available on Precision 3660 download page for 13th gen, suggesting that the HW is the same

I had all the latest updates and drivers installed but still no luck.