Conti

Perhaps try using a mac pro 5,1 smbios.plist... I have an i7 920 myself so I'll post the one I use here. That often fixes IOAPIC errors, but not always... I've not run into this particular issue myself so I'm really not sure where to start tbh but smbios.plist seems the first logical step. I don't think using patched IOACPI should be required on most x58 systems. Copy and paste the following to /Extra/smbios.plist - edit the serial number to something else... SMbiosversion MP51.007F.B03 SMboardproduct Mac-F221BEC8 SMfamily MacPro SMproductname MacPro5,1 SMserial CHANGEME

You put it under PCI0>PEG0>GFX0.... That is the code I use on my MSI 6870 Hawk btw... Good card.

Sure it's possible, I don't have a code example for a 4850 but you can probably adapt the code from my 6870 to some extent, or at least use it as an example... Device (PEG0) { Name (_ADR, 0x00030000) Device (GFX0) { Name (_ADR, Zero) Name (_SUN, One) Name (_PRW, Package (0x02) { 0x09, 0x05 }) Method (_DSM, 4, NotSerialized) { Store (Package (0x0E) { "@0,name", Buffer (0x0A) { "ATY,Gibba" }, "@1,name", Buffer (0x0A) { "ATY,Gibba" }, "@2,name", Buffer (0x0A) { "ATY,Gibba" }, "@3,name", Buffer (0x0A) { "ATY,Gibba" }, "@4,name", Buffer (0x0A) { "ATY,Gibba" }, "model", Buffer (0x13) { "AMD Radeon HD 6870" }, "hda-gfx", Buffer (0x0A) { "onboard-1" } }, Local0) DTGP (Arg0, Arg1, Arg2, Arg3, RefOf (Local0)) Return (Local0) } }

Ensure your SATA is set to run in AHCI mode in your bios setup, if this is a USB try using using different USB port or chameleon USB fixes.

With myHack 2.x you need to use the "Install Chameleon and Extra" targeting your / device after initial OS X installation, the bootloader is not installed during the OS X installation. This is going to be changed in myHack 3.0

PS: I strongly advise against the use of xfail or anything from kexts.com, xfail is worthless and need not be used under any circumstances, kexts.com can be used but only as a last resort if you can't find any other source of what you are looking for.

Since it works after you have plugged in a usb keyboard and unplugged it again it sounds to me more like you have a setup assistant problem, it's something a number of people using ps2 keyboards run into... Usually after getting through the whole installation process that minor annoyance goes away though. Does this happen to you on every normal system startup?