Based on one recent user accepted solution of same issue you need the Dell latest driver for XPS 8840. RTX3060_RTX3060Ti_RTX3070_RTX3080_RTX3080Ti_RTX3090_VBIOS_Update.exe NVIDIA GeForce RTX 30 Series Firmware Update Utility
I have two XPS 8940's with i7-11700 processors and RTX 3060ti cards from the factory (Costco specials). I'm using a MSI PS321QR monitor. I get the 3 Amber, 2 White (PCI power Failure) error code when I start my computer with the monitor plugged into the DisplayPort connection on the graphics card.  Here's where things get weird: starting with the monitor plugged into HDMI on the card doesn't cause this, starting with the monitor plugged into DisplayPort or HDMI on the motherboard also does not.  If I start the computer in one of the configurations above that work, and then switch to the DP on the 3060ti, there is also no problem. The lights don't actually cause any issue during gaming performance (no crashes or anything), but they are annoying and indicate something could be wrong/fail in the future.  I've tried different ports on the graphics card (no change) and I've tried replacement graphics cards in both computers (no change).  The tech that brought the replacements also switched my motherboards, but the CPUs wouldn't work with the replacements, so we switched back.  Any ideas on what is actually going on?  Edit: I forgot to add that I can start the computer with the monitor plugged into the DisplayPort on the graphics card without triggering the error code IF the monitor is off and only turned on once the computer has fully booted up.
XPS 8940, 3 Amber, 2 White lights, plugged into 3060 Ti DP