HI
I have the same system,
X58A-UD3R/I7-960/8gb-DDR3/GTS450
I tried to use these links EFI and the SONOMA.raw image, but I have 2 issues:
1. After flashing the image in a USB flash disk, at the verify step with the balenaEtcher App I have this error: "Something went wrong, if it is a compressed image, please check that the archive is not corrupted. The writer process ended unexpectedly"
Also, I tried to use the Win32DiskImager and the SHA1 is the same. so, I guess the issue can happen to cause the USB flash drive and change that, but still, it's not resolved
2. After flashing the USB flash drive with my laptop, I tried to use that with the PC for boot (I did that with default EFI and CLOVER EFI, Also I tried to use the GenSMBIOS to configure the config.plist file, then all SATA modes on the BIOS setting are set to AHCI), but I got stuck on the "Verifying DMI pool data .............. ", command line got to the next line, and then did nothing
I hope to can find a solution to this, cause I need them