Nvidia FX5600 Sync Problem with Some Resolutions (Soft-15KHz/VGA to SCART)

[raindrop]

Couple of years back I have decided to build MAME arcade machine, so I got an old Grunding TV (50Hz/60Hz) with SCART.

Last week I had some time and I gave the project a go.
I assembled the PC (Celeron 2.5Gz, 512MB RAM, GeForce FX5600), and build myself a VGA to SCART cable (this schematics).

The Problem

The problem is that every time I start a game that has a resolution below 384x288 the picture goes out of sync. This happens not only with MAME games, but same thing apply when I am changing the Windows resolution manually.

I have tried multiple ForceWare drivers (78.01, 66.83, 81.85, 94.24, 175.19) and different modelines but nothing seems to help. Every time I go below 384x288 (352x246, 321x250, 368x240) this problem appears, and if I am on higher res (400x254, 392x240, 384x288, 384x240, 384x224) the picture seems fine.

It is frustrating because lots of the games I want to play are on lower resolutions. 

Anyone have clue about solving this problem? Is it the drivers, video, TV or the cable?
How do I approach the problem?   

The PC is on Windows XP SP3 and I am using Soft-15KHz.

Couple of photos illustrating the problem.

[JDFan]

It's been awhile but IIRC the Nvidia FX5xxx series cards had some problems (Nvidia cheated in order to get faster benchmark scores on the cards and do not follow some of the implementation Specs of some shaders etc. and take shortcuts that can cause problems ) - SO it might be a problem with the GPU 

I had an fx5700 when Oblivion came out and it had real problems with that game's shaders where anytime certain shaders were used the FPS would drop to less than 1 FPS until Bethesda released a patch that turned certain shaders off and added an Ultra Low setting specifically for that line of cards.

Have you tried 163.75 ( http://www.nvidia.com/object/winxp_163.75.html ) (wikipedia lists it as the last known good XP driver for the FX5 series cards !

    Windows 2000, 32-bit Windows XP & Media Center Edition: 175.19 released on July 9, 2008;

    Note that the 175.19 driver is known to break Windows Remote Desktop (RDP).[19] The last version before the problem is 174.74. It was apparently fixed in 177.83, although this version is not available for the GeForce 5 graphic cards.[20] Also worth of note is that 163.75 is the last known good driver, that correctly handles the adjustment of the video overlay color properties for the GeForce FX Series. Subsequent WHQL drivers do not handle the whole range of possible video overlay adjustments (169.21) or have no effect on those (175.xx).

 

[raindrop]

JDFan, thanks for pointing the right direction. 

I have changed the video with GeForce4 MX 4000 (66.83) and now all the resolutions previously not synced are synced properly.

My next problem is the top and bottom overscan on some of the games which I don’t know how to fix.
I guess I have to start checking the forums for a solution, but if anyone has an idea, don’t by shy and drop a line.