D-an-W

System Preferences > Sharing > Computer Name ...is it blank?

sirlou, I will PM you a link to the files I use to install 10.8.2 on a blank drive, the only thing I have removed is the Serial number as I use a genuine one (See "NEEDSERIALHERE" in Config.plist, two places) and I commented out my 1920x1200 resolution setting in rEFIt.conf as I don't know your native setting.

For installation I use it on a USB stick installed with the default settings but don't forget to format the stick as advised in the installer replacing the * with the number of your USB stick...

Need to format as Fat32 on Win or on Mac as below.
1. Erase as MS-DOS (FAT) with Disk Utility first.
2. diskutil list
3. diskutil unmount /dev/rdisk*s1
4. newfs_msdos -v Fat32 -F 32 /dev/rdisk*s1
5. diskutil mount /dev/rdisk*s1

The USB files are the same as the files I used once installed but you can remove this "EFI/OEM/EP45-UD3P/Kexts/10.8/IONetworkingFamily.kext" (It's not needed after you run Kext Utility) and you install it to the hidden EFI partition on the boot drive but we will get to this once you are booting from USB ok.

I will also include my custom DSDT which gives me audio without any patching and I have removed AHCI_3rdParty_SATA.kext as I don't know if you have that add-on SATAIII adapter
Once installed the only thing I edit in 10.8.2 is com.apple.mDNSResponder.plist to prevent the system waking from sleep every few hours to check the network connections.

Basically, install Clover USB with the default settings and then delete the EFI folder it creates, replace it with the one I send and give it a shot, if things don't seem to work I will take some shots of my BIOS settings as a start point.

My hardware is below...

I changed the Audio layout in my DSDT and now I don't even need to patch AppleHDA.kext

There are now only three kexts used here, FakeSMC.kext (Can't not use this!), RealtekRTL81xx.kext (For onboard LAN) and AHCI_3rdParty_SATA.kext (To correctly name my 3rd party SATA III adapter).

With Clover installed on a USB stick, I can boot a vanilla Mountain Lion 10.8.2 installer on the same USB and the proceed to install OS X without any issue at all.

The only other file I patch is com.apple.mDNSResponder.plist to stop the machine waking from sleep every few hours to check the network but this is optional of course.

I use Mountain Lion 10.8.2

You need to patch AppleHDA.kext for sound (Same method as always) and I use Lnx2Mac's RealtekRTL81xx.kext for the two onboard LAN ports.

Whats the largest drive anyone as used as a storage only device on this motherboard (Not boot drive)?

My 2TB drive is getting ready for replacement and I wondered if a 3TB would work ok?