It's the safest way, but I suspect that if your NVRAM is corrupted with the wrong checksum for the volume, efiflasher can't upgrade correctly and you will get a brick down the road.Is there much risk of bricking even when using the Apple-sanctioned method, via an unmodified macOS installer?
One simple way to check this that I learned yesterday is running AHT. If AHT don't show your serial number, just ?, don't upgrade your BootROM before reconstruction.
This GitHub page has links for all know AHT versions at Apple servers: https://github.com/upekkha/AppleHardwareTest
You can install Apple AHT on a pen drive and run/check for the ? easily. If you have a Mac Pro 2009 and it's running the MP5,1 firmware, get the MP5,1 version.
[doublepost=1539325331][/doublepost]
Is windows the common denominator? Like my machine. Would be interesting to compare before and after a windows install.?
If you have multiple Windows signing certificates in the private part of the NVRAM, you can check this with binwalk, you can start to worry.
You can install binwalk with homebrew.
Also those wings px1's have been as out for sometime on that eBay store. Unless they just don't want to sell to us Aussies
Adorama had Angelbirds Wings PX1 in stock yesterday, I bought another one.
Last edited: