What does this code really mean? The manual states "DXE IPL is started". My system stops after displaying this code during POST. It then beeps three times, short pause, then three more beeps, then nothing. Fans are spinning but nothing displayed on my monitor. This is the third time its happened to me with all three of my BIOS' being un-flashable to correct this error and now my system is unusable since none of the BIOSs appear to work/function.
 
System Specs:    Z390 Dark
                         i7-8086 at stock settings
                         GSkill Trident Z, 3200MHz, CL 14-14-14-34 1.35V, 16 GB (2 x 8GB; F4-3200C14D-16GTZSK)
                         EVGA GeForce GTX 970 FTW+ Gaming
                         EVGA SuperNOVA 1600 T2, Titanium 1600W

The RAM LEDs are red upon start up but quickly go out about half way through the POST process but never turn white. Once the POST code reads 4F, the LEDs are off - neither red or white. The rest of the MBs LEDs are white.
Tried clearing CMOS. No change in behavior on any of the three BIOSes.
Removed both sticks of RAM, cleaned them per your instructions. Tried one at a time in each slot with each of the three BIOSes. Quite a few combinations. No change in behavior.
Unfortunately, I don't have any other DDR4 around the house to try. My parents' system uses DDR3. 
 
Something to keep in mind, when this first started happening, 6 months after building the system, simply switching to another BIOS fixed the problem. Unfortunately, I've burned through all three BIOSes now. First BIOS died at 6 months while the next two died after 3 months. My board/system is approx. 1 year old. 
 
Kevin

So, you think the BIOS chips are bad? I guess I could start there and see if the new removable BIOS chip dies in the future with the same 4F post code. Still doesn't explain why this happened.
 
By the way, the Intel i219V Gigabit NIC stopped working about a week before BIOS 3 stopped working with the 4F post code error. I think my particular board is having some serious issues. I'll see if EVGA will replace it.
 
Kevin

RMA submitted. Just waiting to hear back from EVGA. 

Wasn't OC when this happened. My memory is advertised to run at 3200MHz @ CL14 once you load XMP. Default speed is 2133MHz. Don't remember what the CL is at their default speed.
In all three instances of this happening, I was running my memory at 3200MHz, CL14 and when I powered up my system in the morning, it would lock up at F4. It worked just fine the night before when I shut my system down. Then it sat overnight, powered down and the next day (late morning, early afternoon), it would happen. Doesn't matter much now as my board is on its way to CA for a replacement via RMA.
Unless running my memory at 3200MHz, CL14 killed the BIOSes. Not sure why that would happen. Its not like blazing speed - 5000MHz or something. Memory is currently installed in a new system and running at 3200MHz, CL14 just fine with no issues.