My 3900x won't even get to BIOS/UEFI. I'm stuck at the white led forever.
On the Strix X470-F, the build was running a 2700X just fine, 5 minutes later, when I try to boot with the 3900x: White led (same as other boards which were brand new). Put back the 2700X in this morning: boots just fine.
What did I forget to test ? What can I do next ?
BIOS was flashed to the latest version on the 3 motherboards tested.
Not only that, but the X570-F supports it right off the bat, but I STILL updated the bios to the latest available version (yesterday) and that cpu didn't work. Strangely enough, another 3900X works just fine on the same motherboard.
My actual motherboard (a X470-F) had its BIOS updated 5 days ago, while the latest BIOS was released weeks ago. It is stated in the release notes of an older BIOS version for the same motherboard that it, in fact, supports Ryzen 3000 series CPU.
I cannot update it more than it is right now, I'm on the latest version.
only reason I bring up the BIOS as it is often overlooked
there are known issues with some batches of Ryzen 3000 series processors
NB the long thread for the R5 3600 woes
I fear that you're going to end up looking for an RMA...
Suggest verifying one (or two) of the X570 boards and their hardware with the existing 2700 processor. Generate a known good configuration with known latest BIOS...
Once you've booted to BIOS, run a MEMTEST86 on your selected X570 to validate the RAM XMP configuration and selected clock rate.
Then reinsert the 3900x into the known good motherboard/memory/bios configuration.
I know the whole thing is frustrating, but remember testing basics. Start with known good and only change 1 thing at a time between tests...
Best of luck!