I recently acquired a Hercules 3D Prophet GeForce III card and although it seems to be working, it has some quirks. Keen to know if this is just how this card is, or if I need to go fault hunting.

Connected to my modern LCD over DVI (via HDMI passive adapter) - I get a super noisy signal when in DOS resolutions. I also get sync dropouts (black screens) frequently while POST and initial Windows 98 loading takes place. I'm guessing these are tied to the resolution changes that happen during boot time. The whole time, that super noisy signal is present.

If I boot in to DOS - I continue to get that noisy signal. I also get some jank on the right hand edge of the screen; flickering pixels etc.

As soon as I am in Windows 98 - the signal is perfect.

Benchmarks run without issue and performance seems where I would expect it.

If I go to Properties -> Settings -> Advanced I get a sync drop when the next windows opens and I get another when I click on the GeForce3 Ti 500 tab.

If I hook up a VGA connection - all the jank goes away. No more noisy signal in DOS resolutions. I get a brief flicker of something when the Advanced properties window opens but nothing else.