Anyway to overclock the RAMDAC in linux?

[Xevious]

I was curious if there is anyway to overclock the RAMDAC in linux?

In linux I am limited to 400 MHz, however in windows it will let me do custom modes over 400 MHz, I got it to do 420 MHz no problem.

This isnt a huge issue but I was wondering if there were any nvidia driver overides or something where it would let me specify the RAMDAC speed?

[Thunderbird]

For what purposes do you need such modelines? It must be insane high resolutions at very high refresh rates. Normally you want a higher pixelclock to get better image quality but also the image quality tends to decrease at these high pixelclocks. I can't easily explain why without getting way too technical. Lets just say that the output 'circuitry' won't perform optimal anymore. You can cross the limit of the card a little but then the signal quality only gets worse and second the VCO (voltage controlled oscillator) which in the end generates the pixelclock (in combination with a PLL) is limited to a certain frequency. I'm not sure where the limit lies for your card but likely it is between 400 and 500MHz.

Further to take advantage of a high pixelclock your monitor should support it too. If the bandwith of the monitor ('the max allowable pixelclock') is less than the pixelclock the signal quality also decreases which will result in less quality.

[Xevious]

well it looks fine in windows @ 420 MHz, and i get a higher refresh rate, its not a huge difference because its only going from 62 Hz @ 2560x1920 to 64.4 Hz.