MORE VGA NEWS!!! - Should have listened to Netkas !
I finally got my Gainward HD 4870 1024MB Golden Sample working
I've made a custom ROM with the original "normal" BIOS of the card, and here the results :
- you MUST have HDMI-DVI+DVI-VGA adapters connected to HDMI port for DVI-D and VGA ports to work
- DVI-D fully working
- VGA fully working (i've got 1920x1080@60Hz)
- DVI-D+VGA KO (only DVI-D get signal)
-
After reading this I realized there was one set of things I hadn't tried.
So I put the DVI-VGA adapter on each output of a 512 Dual DVI card while connecting Dell 2407 on other connector with VGA and.......................
When the adapter is in the LOWER port (Dual-Link one) and the VGA is in upper, THE VGA WORKS !!!
Well, sorta. It appears to not be getting an accurate EDID as it can't guess what display it is and just calls it a "VGA Display". Most of the res options for it don't work.
1920x1200 is there..but at 76Hz....not LCD frendly.
I had flashbacks to when we were first "breaking" the Nvidia cards. First was 5200 Ultra from which we got regular 5200 cards to work. If you flash the Mac 5200 Ultra ROM to a PC 5200 Ultra, it will work, BUT ONLY VGA COMES FROM DVI PORT.
A very clever man came along named Arti figured out what was happening with our DVI.
The display channels were mixed. ie, the EDID taken from port 0 determined the output to port 1. We never disclosed just how simple this was (once you deciphered the Forth) If you go in to Hexedit and search for "3f3e" and "3736" and SWAP them, suddenley the DVI works. (previously undisclosed secret). You can try this at home, works on all 5200 Ultras.
When we started work on 6800 cards, we had same thing, but more complicated. But if you flash an OEM Mac 6800 ROM onto a PC 6800, you will get VGA only.
WHilst we were hacking our way through this mess, Arti encoraged me to get a strange splitter. It plugs on to a DVI-I and splits it into a VGA AND a DVI-D. This helped diagnose the 5200/6800 channel switching.
I dug through the drawer and got the splitter out. Sure enough, there are TWO SEPARATE SIGNAL IN THAT DVI PORT.
By hooking both sides of this adapter to my 2407, I got two separate images / feeds from the two halves of the splitter.
The DVI one got EDID right, the VGA still got no EDID.
So, what we need is to find where the display connections get channeled in the ROM and switch them.
Most likely, the physical traces on the board are switched, now we need to switch them in the ROM, and we MAY get VGA.
If I had tried Netkas' patented DVI adapter trick earlier, we would have known this much sooner.
Anyone else with working Dual DVI who can try this should (without the wacky splitter anyway)
GOnna try with the Single DVI Diamond now.