Currently I have a 9800 GT which does not use dual link DVI, only VGA and regular DVI.
I am getting a Acer 120 Mhz screen in a few days and I'm wondering if I will be stuck with 60 mhz until I get a better GPU?
More aboutdual link
All video cards since x800 and 6800 series had dual-link to my info. So your 9800GT should support 120Hz when you use a Dual-Link cable (thick ones) but yes, your GPU will most likely not keep up as 120Hz cuts your FPS in half.
Yes you need a dual link dvi connection if your monitor is 19 x 10/12 or higher and has a 120hz refresh rate.
You can tell if you have a dual link connector by if there is a gap in between the pins. Wikipedia has images which show the different pin layouts.
Don't you mean Single Link is the one with a gap in the middle?
a 120hz monitor can display up to 120 frames per second. But unless your card is fast enough for those speeds. You would see no gain.
Games like shooters with fast movement benefits most from high frame rates but also requires the most graphical muscle. Not sure what games you are playing but a 9800 GT might not get to 120 frames.
While RTS and RPGs can look smooth even at 30 FPS but requires less graphical performance.
Now the new question is, Is Dual-Link enough for 240Hz? Lots of TVs now have 240Hz.
No and those TVs aren't actually 240 frames per second. The signals are 60hz but there is a small GPU inside the TV which takes the 60 FPS signal and creates intermediate frames with it. So even a single link cable would work.
Also 240hz TV for computer is bleh because to create those extra frames you get like 2 full seconds worth of input lag.
Displayport can technically do 240hz but what game are you playing? Some old games maybe. Or the low end ones like Modern Warfare 2 or L4D2. Otherwise 240 FPS is hard to reach.
I am gaming on 2560*1600 and I can't even max settings witout going under 60FPS for games like Bad Company 2. Maybe in the future we have crazy video cards that can do 2560*1600 at 120hz. Honestly 120hz isn't necessary.