advmame on 26" 15Khz monitor woes

[skydemon]

Hey guys, Ive got my 26" Nanao 15/25 monitor running both on 25Khz and 15Khz. When its in 25Khz mode there is no problem, however in 15Khz mode I noticed some strange effects on the screen. (its a bit hard to explain but ill try)... basically when there is any vertical movement (say a character jumping up and down) there are a few rows of pixels that dont seem to be updating in sync with the rest of the display, its almost as if there is a row of pixels that are missing (always on the same row of pixels). Has anyone seen this before, can anyone help? Cheers

I hope that makes sense, if not ill try uploading a pic of the screen

[stellarola]

I had no idea that advmame could do 25khz...

[Silver]

pic of the screen would be helpful...

you seem to suggest that a few rows update out of time, but also mention a row is missing?

First thing I would do is feed a 15Khz signal to the monitor without advmame, and ideally from a completely different source (not your computer) to find out where the problem is coming from.

[desmatic]

sounds like its a vsync issue which could be caused by a number of things.  What's your setup?  Particularly your video card and OS?

[skydemon]

its a Geforce2 running on DOS, like I said earlier there's no issues when running at 25Khz, only 15.

Ill try and get soem screenshots soon, cheers