Refresh Rate on an external monitor on 24" iMac

Question

I'm using a 24" Apple iMac running 10.5.8. I recently purchased a Hanns-G HG281D, which is a 28" LCD.

It's connected to my computer like this:

iMac -> Mini DVI to DVI adapter -> DVI to HDMI Cable -> Display:

Unfortunately, there's a nasty flicker in the screen. My first thought was that it was a refresh rate, unfortunately, I can't change the refresh rate for the display. I can't seem to get a screen grab with the menu open, however the following are the options:

1. 50 Hertz (PAL)
2. 59.9 Hertz
3. 60 Hertz (NTSC)

Number 1 and number 3 are greyed out. I can't select them.

For the record, I'm an Australian who recently emigrated to the USA, and I brought my iMac with me. So the iMac is an Australian model (for whatever it's worth) and the monitor was just purchased from Newegg, and as such, is an American model (again, for whatever it's worth).

I've read a bit about acceptable timings for displays, and it would seen the 2600HD in my iMac should be able to drive the display to at least 60hz. (Ideally, I'd like to see 75, as eye strain is a big issue for me, and part of the reason I'm moving to a larger display).

Answer 1

I solved this particular issue by using VGA instead of DVI->HDMI.

I didn't use VGA because my housemate's display did not work correctly under VGA on the same machine.

Some things I noted that may be of future reference to other people with this issue:

• When I plugged the monitor in via DVI -> HDMI, the computer set the refresh rate to 59.9 hz.

• Additionally, SwitchResX was reporting all sorts of timings that just didn't seem right. This leads me to believe that there's either an issue with the cable, or there's a problem reading EDID information from a monitor connected in this fashion.

• When I plugged in to VGA, the monitor picked up the refresh rate at 59.9 hz, but instead had the proper list of refresh rates to choose from, and the flickering stopped.

There's been a lot of information regarding this issue, especially when attempting to use a Mac as a HTPC. Unfortunately, the problem is on Apple's end - their software is not playing ball with other displays.

(You can prove this with Boot Camp, most displays appear to work fine on the same hardware)