So I have a Diamond Speedstar pro, it's essentially a GD-5429 reference implementation from what I can tell. Anyway, yesterday, i went to use it and when the computer POSTs, i noticed the monitor comes on but it says "out of range". Tried everything, including a few other motherboards to the same result.

I decided to dig in and see what's going on. So I check the hsync and vsync pins on the dsub connector with my scope and noticed the timing is WAY off. hsync is something like 80mhz and vsync is at 160hz. After poking around the data sheet, I see that the gd5429 and all the related sync pulses can either come from pin38 on the ISA bus or an on-board 14.318 crystal.

So I probe the crystal on the card and its running at 42.9xxxxx mhz, almost 3x what it should. I decide to change it out, and same result.

What's weird is when I power on the machine while probing the crystal, 3 out of 5 times, the timing comes up correctly at 14.318mhz and the card/display works.

I checked for bad traces, bent pins, etc, but can't find anything.

I'm totally stumped, what the heck would cause a crystal to oscillate at 3x its speed, and what about power cycling the card/probing it makes it work correctly part of the time?

Anyone have any idea or suggestions?