BIOS dump of a PAL version of the card can work, assuming one can be found.

But I'm the first owner of this card, back then it was bought brand new in a PAL country. So a PAL one just doesn't exist?

Does anyone have saw one of these cards booting up in PAL on the S-Video?

Fiena wrote on 2024-01-19, 00:21:

I have a nVidia Geforce4 MX 4000 PCI card in a Compaq D500 (Celeron 1,3GHz, WinXP) connected to a TV with S-Video for playing so […]
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I have a nVidia Geforce4 MX 4000 PCI card in a Compaq D500 (Celeron 1,3GHz, WinXP) connected to a TV with S-Video for playing some older games.

The TV is a PAL 50Hz one, but the video card always boot up in NTSC 60Hz mode so the POST and Windows XP logo is NTSC. It switches to PAL 50Hz when the Windows driver is loaded and works fine then.

But I really would like to have it booting in PAL 50Hz mode so the POST and logo will show correct on the TV.

There's no jumper on the card to set NTSC/PAL. But someone said it was maybe possible to mod the video BIOS for it. I searched for NiBiTor and only found versions 5.4 and 6.06, both only support Geforce FX and up, no Geforce 4. I can't find older versions and don't know if those support Geforce 4.

Now I found another topic (Re: VESA Fix Utility Listing (for old video cards)) which mention X-BIOS editor for older nVidia cards. This one do support Geforce 4, but the TV-out options are greyed out. In the "help" it says "Do not work on GeForce 4 MX series" in the TV-out page.

Is there any other option to let this card output PAL 50Hz on S-Video at boot up?

Have a look at this BIOS editor . It might work .
Ray Adams' nVIDIA BIOS Editor :
download/file.php?id=101163

Alternatively, maybe share a copy of your current BIOS dump so maybe someone here can have a look at it.

That one has the same GUI as the X-BIOS editor I tried. And in this one the TV-out settings are greyed out too 🙁

In the meantime I tried a v4.0 of NiBiTor too and it didn't support Geforce4 either.

I've attached a copy of the video BIOS from my card.