2560x1440 over HDMI?

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2560x1440 over HDMI?

I have a 27" monitor that is HDMI 1.4 compliant and can recieve the full resolution over HDMI. But I'm having problems getting my Mac (Macbook Pro w/ Retina Display) to select that resolution under OSX. I know the hardware is capable, because if I boot into Windows, I can run 2560x1440@60Hz w/o issue through the HDMI port.

So I tried using SwitchResX. I tried forcing 2560x1440@60, but it just wouldn't work. I then tried lowering the refresh rate to 40Hz - lo and behold, it works. So it seems the HDMI port cannot function over 165MHz under OS X. But it isn't a hardware limitation since it works fine under Windows.

So has anyone gotten such a setup to work? If so what's your trick? I know I can just use displayport (in fact, I have such a cable on order) - but I was hoping to leave my two thunderbolt slots open for an ethernet adapter and eventually the firewire adapter when it's released.

MacBook Pro with Retina display, OS X Mountain Lion, 2.6GHz, 16GB RAM, 512GB SSD

Posted on Jul 31, 2012 6:22 PM

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Answer 1

cynikalX

Level 1

0 points

Aug 22, 2012 9:41 PM in response to hyderali91

sorry i am not sure what causing it from working over 165Mhz (how did you calculate that figure anyway if it's 40Hz you're limited to @ 2560x1440 ? Also can you visually tell the difference of 40Hz from native 60Hz? Imagine if you were playing a high frame rate full-res game maybe then..

i am actually really interested in going this way (using only HDMI ports), can you share what brand/model 27" monitor you have that you even got 2560x1440 working even if only at 40Hz?

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Answer 2

hyderali91 Author

Level 1

10 points

Aug 23, 2012 4:33 AM in response to cynikalX

Hi, I was using the "Auria EQ276W" from microcenter. It's a $400 IPS panel (same panel as the apple 27" if I'm not mistaken). With that said, the low price does show elsewhere -- the OSD is clunky, and the stand *****. There may be other monitors that support it at 40Hz -- I know that some have successfully got the Dell U2711 to work at 2560 over HDMI (in Windows) by using a hacked driver.

Anyway, I used switchresx to create a custom resolution. When doing so, it shows you the frequency required for that specific resolution at the timing scheme you desire. I used CVT-RB. As far as any noticeable differences at 40hz... Mostly I noticed the cursor didn't move as smoothly, and other animations also seemed choppier. It was definitely usable though. Videos looked fine for the most part.

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