I found probably the same BIOS as Riikcakirds have:
Inno3D 7900GS PCI-E 256MB http://www.techpowerup.com/vgabios/127400/127400
But this image doesn't work on my 7900GT too. VBIOS loads but it detect insane 3GB of VRAM and any graphics mode doesn't work, even basic VGA, just black screen and monitor off on any VESA mode. So it seems I'm done, I would need 7900GS to test...

I'm not entirely sure if this is the same vBIOS that Riikcakirds wanted to provide or not, but the version number and release date are exactly the same (5.71.22.41.00 dated 08/09/06):

https://www.techpowerup.com/vgabios/20457/20457

Differs in MD5.

Ok, I give a try during weekend, I have 1 PC with 7600GS, maybe it would be better compatible than GT.

With a deeper comparison, the vBIOS you posted converges also in terms of frequencies, as well as revisions. It seems that this is it (I saw your message after I left mine).

My question is: if we consider alternative solutions to the problem, is it possible to hard-set the output frequency somewhere in vBIOS? For example, what would always be 120 hertz (Instead of 60 by default)?

I have a 7950GT PCI-E and tomorrow I will also try to test both found vBIOS. Although the performance of the 7950GT is not the goal of the experiment for me, since the G71 no longer works with ForceWare 77.72 (and newer ones cause problems). I'm using G70 based graphics cards which are supported by 77.72 (INF Modification), however found vBIOS though booted from G70 via RamBios (Also, yes, with 3GB message) but games didn't start (Black screen).

I don't know if there is some freq. table that is used by vbios during init. But even if yes, it would not be good idea as many LCDs can't sync over 60-70Hz and you can get a WTF moment after some years you will forget that you did that mod 😀

I looked at GPU table and all 7900 GS, GT, 7950GT should be G71, 256bit memory bus while 7600GS is G73 with 128bit memory bus so it seems it will not work with this vbios. Maybe we could try to find Inno 3D vbios for 7900GT with the same version like GS.

OK, I just tested your found vbios: https://www.techpowerup.com/vgabios/20457/20457
and doesn't work too on 7900GT (3GB, no signal in any gfx mode). It differs only in a few bytes from mine found verison.
I didn't find same version for Inno 3D 7900GT, the closer I found is ver 5.71.22.29.00 : http://www.techpowerup.com/vgabios/2616/inno3 … 00gt-256-060519
The image is a bit greater. It loads fine, display correctly VRAM size, works all VESA modes but refresh rate setting doesn't work, always 60Hz 🙁

On TechPowerUp the highest vbios version for 7900GT is 5.71.22.38.00 and for 7900GS it is 5.71.22.53.02, maybe nvidia fixed the bug in newer version and break it later again? I think that card manufacturer is less important than the version number.

Apparently, the 7900GS is something very special...

I just checked the vBIOS data with the 7950GT (G71) and saw the same results as with the G70 yesterday! Namely, the message about 3GB, a black screen when starting games, as well as UNIRFRSH freezing when trying to autoconfigure (If you are reading this, you probably have a 3DFX video card). All the same. It looks like we'll have to look for the genuine 7900GS, otherwise there's probably no way to check it. Although, perhaps, the NVRAM needed to be cleaned / reset the CMOS or BIOS settings, maybe something else was left somewhere from the previous G70, but I think the probability of this is close to zero. Perhaps, for the correct determination of the amount of memory, it is the real firmware that is required, and not running through rambios. However, I think it's easier to find a genuine 7900GS for such experiments (And preferably also from Inno3D, as far as I understand).

RayeR wrote on 2022-12-01, 00:41:

I don't know if there is some freq. table that is used by vbios during init. But even if yes, it would not be good idea as many LCDs can't sync over 60-70Hz and you can get a WTF moment after some years you will forget that you did that mod 😀

It is possible to use such a modified vBIOS, at a hard-coded frequency, for DOS games only, running it immediately before the game (Together with UNIRFRSH) via RamBios, and unloading it from memory after their game exits. So not the slightest risk. I already did this when I used the GeForce 5600 U AGP, which also initially had a wrong VBIOS. Fortunately, I found a normal one, with which UNIRFRSH worked, but did not flash it (It was not very suitable for this card under Windows for some other reasons), I used it as needed only for DOS and games, of course.

It would be almost ideal if you create several copies of the vBIOS at once, each for its own refresh rate (85, 100, 120, 140, 144, 150, 160hz) and run the necessary vBIOS, depending on the specific game. But this is an extreme option, if nothing works out with UNIRFRSH (Although one can already say that it doesn't. For 7900GS, even if successful, is not the best option in terms of Windows, because G71 and only 80+ drivers).

Ok, dynamic loading is fine. And is there some tool to mod vbios refresh rate? Or did it already someone hacked manually? How the data structure in vbios looks?

Yes probably we need real 7900GS for further tests. I will try on 7600GS but will not 99.9% work. I don't see much cards arround, also a lot of them died due to poor ROHS solder in combination with heat after years...
Also it may be discovered that the refresh code is present only in GS and was removed in GT vbios because they need make more enough space for other code and it could't be patched as simple way like when refresh code is there but broken, who knows.
I think that NVRAM/CMOS is not involved in this case.

RayeR wrote on 2022-12-01, 16:38:

Ok, dynamic loading is fine. And is there some tool to mod vbios refresh rate? Or did it already someone hacked manually? How the data structure in vbios looks?

I've come across this method as a recommendation for video card owners from ATI (Who wanted to change 60hz on their CRT monitors). Moreover, this method was mentioned as the only one possible for DOS (Applicable to ATI cards). It was about manual modification of vBIOS in the HEX editor. I don't remember all the details, so I'll try to look for more information about it. As for nVidia, I have not seen this, Unirefresh or VBEHZ is recommended everywhere.

Now, after searching, I found the RadEdit program:
https://radeon.ru/bios/util/radedit/eng/

for modifying ATI vBIOS, which, starting from version 1.1, seems to allow you to set the refresh rate in DOS (Did not check):

Nice tool, I never used ATI on desktop so didn't approach this. I used UniRefresh in CRT age until my GF4MX440....

RayeR wrote on 2022-11-25, 04:40:

Hi, this sounds interesting and a bit incredible for me as I have some GF7xxx cards and tried various vbios versions (older and […]
Show full quote

Hi, this sounds interesting and a bit incredible for me as I have some GF7xxx cards and tried various vbios versions (older and newer than your 5.71.22.41.00L) but with none the refresh rate setting worked. I just belived that nvidia discarded this feature from vbios a generations before GF7. If it really wors for you then it means nvidia didn't discarded it but it is just some way broken on most cards and it may be fixed. Also it would be interesting if this would apply for other bugs of newer GFs.

Please could you make a vbios dump of your VGA using the nVFlash utility (nvflash --save filename.rom)? Use version 5.80 or similar for this GF. https://x-drivers.com/catalog/flash/video_car … /12054/download
This is the only corrent way to dump nvidia vbios because the vbios shadowed in RAM after boot may be patched runtime at initialization and we need the vanila version from flashrom on the card. Newer GFs even has vbios >64kB so this is the only way to dump whole flashrom.

Also I'd like to know some details how you patched the game for 1600x1200. I tried to modify DOS graphics application 3D Studio 4 (Vibrant VESA driver) to add 1600x1200 over 1280x1024 but without success.

I'm getting the card back from my uncle in a few weeks (I give it to him last year, now he's getting a new PC). I can't seem to download NVFLASh from the link you give but I found v4.7 on archive.org, is that older version enough.

One thing I noticed about nvidia cards and refresh rate from years ago using XP, it may give some clues. This was after using using:
https://www.phatcode.net/downloads.php?id=196 - a patched videoprt.sys.

I had a few nvidia cards like 6600GT and 8600GT that would not set refresh rate above 60hz in dos after using unirefresh, even though they are VBE3.0. Now from what I have researched NTVDM in XP only uses the actual video cards bios for VESA and nothing else (no xp emulated vesa bios or drivers). After using the patched videoprt.sys, (to stop xp blocking ports and enable access to the ports that the driver of the videocard lists in the registry) I could set refresh rates above 60hz using unirefresh in fullscreen XP NTVDM. So it seems the function of setting refresh rates in these newer cards IS present in the bios but is blocked in dos??
This was the only reason I found the 'Restart in MS-DOS mode" option useful on Win95 and Win98. Some difficult video cards (like matrox G550 pci) would not enable MTRR whatever I did and also ran at slower memory clocks when booted to dos. Booting to win98, the drivers enabled MTRR and full clock speeds. Then using 'restarting in ms-dos' option the card still had those enabled. THere was no other way to enable those features in DOS.

I though we are talking about refresh rate setting under pure dos, not ntvdm. When Windows are active, then nvidia driver can do various settings on the card so it may then support refresh settings some way/altered by driver. But I wonder if any 7xxx card can set refresh under pure dos...

RayeR wrote on 2023-04-20, 22:21:

I though we are talking about refresh rate setting under pure dos, not ntvdm. When Windows are active, then nvidia driver can do various settings on the card so it may then support refresh settings some way/altered by driver. But I wonder if any 7xxx card can set refresh under pure dos...

I have got the card back from my Uncle. 7900GS. Just to check when I backed up the bios, NSSI , GPU-Z and nvflash 5.91.0.1 all produced different hashes when saving the bios
The bios size is 61,952kb. Both Nvflash and the latest GPU-Z saved the same size but different hashes. NSSI saved only 57,344KB.
You were right about it being a bit of a minefield when it comes to saving the bios correctly and what programs can be relied on.
The bios attached is the one I saved using nvflash 5.91.0.1 from within WinXP.

By the way, I mentioned NTVDM under XP because in my experience only cards that let you set refresh under pure dos will also let you set refresh under full screen NTVDM. (NTVDM and nvidia gfx driver don't touch vesa modes, just pass it to the cards VBE bios.)
With this 7900GS card as well as pure dos I can also set 1600x1200@100hz using unirefresh in full screen NTVDM under XP.