I have an PNY GeForce 8400 GS VCG8400SXEB 256MB PCIe card. Wanting to use its DVI output to a 1080p display.

If it matters, I think it is x1, not x16 (I think this is part of the nvcap string).

I am using an old 40G IDE drive I have. At its top level Disk Utility tells me its FAT and I can't seem to change that, but I can create an HFS+ journaled partition. At the beginning of each install I use disk utility to erase that partition. (see below, I'm not sure if its doing all I think it is)

At ground zero I used iPC 10.5.6 and tried a few installs. nvdarwin 256 didn't work for me, neither did natit. Then I tried nvinject 256 and when I booted after the install I got a gray background (looked like an old X background).. I thought it had failed, but lo and behold I got the registration dialogs and after those I got a 1920x1080 display with background. I had no acceleration. All seemed seemed good except the lack of acceleration.

Section/question A:
so I tried a few things to get accleration. Among of which I copied all NV* and Ge* kexts to a backup folder, removed them, and tried installing a string for nvidia 8400gs 256M from EFI studio (90% sure it was that tool) into boot.plist, and rebooted. I was not a good boy and did not flush kext cache. I got a black screen on reboot after the verbose section of the boot and thus rebooted again into single user mode, removed the EFI string from boot.plist and copied my backup kexts back into place in an attempt to get back to a working screen. It did me one better.. when the boot finished (after exiting single user mode) I had 1920x1080 WITH accelerated QE/CI. Sweet! I thought... but then I rebooted again, and I got was a black screen. So it was working.. and then all I did was shut down and restart, and then it failed.

so question #1 is how did that work at all, and why did it stop?

Section/Question B:
So I thought maybe I could at least get back to 1920x1080 without acceleration.. so I booted iPC 10.5.6 again, erased the install partition, and re-installed, 99% certain with the same settings.. ie. nvinject 256M, verbose, and restart fix (that's it). when I rebooted from the install this time, I got stuck at a black screen after the verbose section (last time I got the grey screen and thru the registration). So it made me wonder if there was some residual bad stuff left behind (somehow, somewhere.. remember I did erase the partition)? Have I inadvertently created another (EFI?) partition that I need to be removing/erasing? ie. I thought I would be back to a "blank slate".. but don't seem to be.

Apologies I've probably badly mis-described several technical details. I'm still very much learning my way around osx86.

Right now I'm just trying to understand how to recover when I try methods that don't work (there seem to be a good 5-6 or more ways different folks use to get the cards to work)

I guess partly in a nutshell:

-when I try nvinject, nvkush, nvdarwin and it fails, I can recover to VESA by simply removing all NV and Ge kexts? (I have to flush caches after this?)
- when I try an EFI string to boot.plist, I can recover by removing that key.value pair from boot.plist? (anything else?)

is this is such a crapshoot b/c the cards don't follow a tight spec?

Part of my homework for tonite is to write down the device IDs and try plugging those in to the kexts. But as I mention in #B, I'm not sure that I'm not getting polluted by previous experiments.

thanks for your patience and ideas.