Maybe the card have not enough juice to run NV45 use more power than NV41.
Can also be a RAM or BIOS issue.
But I would test the PSU before.

Datadrainer wrote on 2023-03-14, 14:26:

Maybe the card have not enough juice to run NV45 use more power than NV41.
Can also be a RAM or BIOS issue.
But I would test the PSU before.

I forgot to write that:
-If on the same pc I install Windows 7 I pass 3dmark (with NV45).
-If on the same pc I change the board with Windows 98 already installed I pass the 3dmark (i.e. I mount the NV45 board without formatting)

So I rule out a card hardware or power supply problem

The problem is somewhat confined to starting apps from MSDOS only (not apps launched from Windows)

Can be a card BIOS issue. Did you try to change/update it?

Datadrainer wrote on 2023-03-14, 15:55:

Can be a card BIOS issue. Did you try to change/update it?

Interesting, do you have any sites to suggest to find the bios?

I've seen flash ROM corrupted by time. It's a track to verify.
First I would make a copy of your BIOS, then try to find a corresponding MD5 or SHA-1 on a search engine. If you find one, then the BIOS is good.
If not, that means your BIOS isn't know by search engines or it is corrupted. To test the second choice, keep preciously you backup. There is a Video BIOS Collection on TechPowerUp, I think you can find BIOSes for your video chipset there. Try to take one having the same spec of your card. The type of RAM matter, FX-3400 have all GDDR3, but who knows. The type of bus matters too but I think FX-3400 still use a PCIe <-> AGP bridge. Maybe someone here can tell. Working frequency matters too but that can be changed with a BIOS editor if needed and at worst your PC will crash. I've never seen a video chipset to die because of overclocking but in general BIOS overclocked are for card with a big cooler. Not the subject but that make me remember I've seen an Athlon Thunderbird emitting nice smoke because the fan of the cooler was blocked by dust and an Athlon XP Palomino doing the same a few second after boot, but without cooler at all this time. You know when you think it's a good idea to not mount a cooling just to test if the motherboard starts. I loved this old Athlons <3 Very festive chips.
For the tools flash, you can find them online. Just check they support your BIOS generation. Some are working from real DOS, some are working under Windows. Don't remember which one for what. Have them somewhere if really you don't find.