Hey all,

I am having an issue I hope you can assist me with.

I followed the instructions and installed Snow Leopard on to an external USB drive (old 80gb IDE HDD inside). The install went fine, within an hour I was successfully booted into Snow Leopard on my PC. Everything worked so well in fact I decided to do the same install on an internal SATA drive. I cleared out one storage hard drive and followed the instructions again.

Originally I was getting a black screen, the error was either SMC related, or "Device in Slot 1" related. Today I happen to have my USB headset plugged in, and when I booted up to test - I heard the welcome music (the music the first time you turn on OSX and go to the registration page) coming through my speakers, but again no video other then the black screen in -v mode. (I also tried -pci0/-pci1 and -x -- none were sucessful).

Anyways, I took out my Video Card ( I have a Sapphire 4870 1GB card ) and switched to onboard video in BIOS. The system booted up fine with no flags. I entered the system with no issues at all and it is working fine as we speak. I turned off the computer and put the 4870 in again and tried to boot, but it went right back to the black screen.

What confuses me is I had to do absolutely nothing reguarding my Video Card when installing to the external USB drive, but for some reason, while installing to my internal SATA drive, my video card will not operate correctly.

(Note: during one of my many tests I copied over the boot file, kernel, /Extras/ folder to my internal sata drive from my working external drive install (i rebuilt the mkext file and changed the UUIDs to the internal.. but that did not work either.)).

Any suggestions on what I can try to do to be able to use my 4870?


Summary:

-- Can boot into OSX with internal graphics.
-- Black screen when attempting to boot with Radeon 4870.
-- External USB drive works fine WITH the 4870 in.

Mobo and GPU:

Motherboard: Gigabit MA-790GP-UD4H
VC: Sapphire 4870 1GB
Processor: Phenom II x4 920 (4x 3.0GHz)

Thanks very much!