Soft-15KHz on onboard graphics?

[TheManuel]

Is there any reason why, in principle, a software like Soft-15KHz or Powerstrip could not be used to output CGA compatible video frequencies out of an onboard video chipset?

Thanks.

[MonMotha]

It's entirely up to a couple aspects of the onboard video.  I will say that most modern add-in cards from nVidia and ATi are capable of these modes, as are I think every single card ever made by Matrox, but I'm not sure about the onboard Intel stuff.  The fact that it's onboard (as opposed to on a separate card) has nothing to do with the ability to hit low dot-clock/low horizontal scan rate modes; it's entirely a function of the electronics themselves.

[TheManuel]

Thank you; that makes sense.
That opens up my possibilities a bit as I can start mucking around with the onboard video.

On more question.
If I get a CGA compatible mode working, I suppose I will get an "out or range" message out of my PC monitor.  How risky is it then to feed the video to a CGA monitor without being sure the signal is indeed ~15KHz or some other in between that the monitor cannot handle?
How is this usually handled? 

[ncflagg]

When I've done it my monitor will simply detect an invalid signal and go into standby mode. I've read that it can cause harm to monitors (probably old crt models) however.

[TheManuel]

Well, I'm on all that concerned about damaging my VGA CRT monitor.  I would expect they have built-in protection against that and I'm willing to take the chance.
What scares me more is when the monitor goes blank as you described, how do I know the signal I have coming out of my video card will not damage the std resolution arcade monitor.  Just because it is out of range for the VGA monitor, does not guarantee it will be right for the arcade monitor.