Do I really have 15khz output?

[Lenin Stimpy]

Hi all,

I've got a tri sync Nanao MS2931 hooked up to my Windows 7 PC via VGA.  I've installed Soft15Khz and it has made a bunch of new video modes available via my NVIDIA GTX 680 video card.  I can select these modes via Quickres and launch MAME games in them using GroovyMAME (not CRT_Emudriver, just GroovyMAME driving the Soft15Khz resolutions).  They appear to be running at 15Khz resolutions on the arcade monitor.

Having read a bunch of threads about the trouble with Windows 7, modern NVIDIA video cards and 15Khz generally I'm a bit suspicious because this all seems too easy - I suspect Windows 7 or the NVIDIA drivers or something are scaling the 15Khz resolutions to 640x480 and pushing that out to the screen (which happy displays this resolution).  Is there a way I can test whether I am getting a real 15Khz output from the video card?

[Lenin Stimpy]

I've tried a couple of native res capable emulators and they all seem to switch to these resolutions happily enough.  I've noticed some resolutions (256x228 for Megadrive/Genesis for example) get displayed shrunk in the centre of the screen, which might confirm my suspicion that something is being scaled and the scaler is failing with this res.  Any ideas?

[Calamity]

If you have a PC monitor around (LCD or CRT) plug it to the video output *once* the emulator is running. The output frequency will be shown on its OSD.

[Lenin Stimpy]

Looks like it is sending out a minimum of 640x480 (unless the Dell LCD I have is upscaling the signal but I don't think it is).  The scanlines on the monitor don't look like 15Khz compared to the output on the screen if I plug my mega drive into it.  Any ideas which component is likely to be scaling everything to 640x480?  I have a Radeon 4870 in my drawer waiting to go with the CRT_Emudriver if this doesn't play out but I'm not in any rush and I'm happy to play around with this to see if I can make anything work.  I was also curious because I could find anyone else who had gotten as far as having the resolutions appear in the Windows resolution change dialogue box but then having Windows fake them out

[Lenin Stimpy]

I put the 4870 in to confirm, and Windows was definitely faking the resolutions.  Working in real 15Khz with the CRT_Emudriver now.  I'd love to know what was breaking the old config though.