for Asrock Z77 Extreme4-M (https://www.asrock.com/mb/Intel/Z77%20EXTREME4-M/index.de.asp)
based on BIOS (EFI) version 1.80 (your OS updates your CPU microcode for you anyway)
added NVMe boot support (using NvmExpressDxe_Small.ffs)
in near-daily use for 9 months now
only issue is: a few times it happened for unknown reason that CSM got reenabled and so boot was not working (black screen). change it back to disabled and everything is fine again
DOWNLOAD HERE (SHA256 d6bdbff98ddbbb7d9a79110b7903ee157de6983369c17cea8e23775465f1dd8d) UPLOAD.EE - z77e4m1.80.nvme-mod.rom - Download
(unfortunately I cannot attach the file directly, so lets just hope the external hoster does not delete it)
z77e4m1.80.nvme-mod.rom.zip (4.2 MB)