Having read Jeff Atwood's blog post on Korean 27" IPS LCDs, I've been wondering to what extent these are useful in a notebook + large display situation.
I own a Lenovo Thinkpad Edge E320 with 2nd gen. integrated Intel graphics. According to the spec from Intel, this should support HDMI version 1.4, and, using DisplayPort, resolutions up to 2560×1600. HDMI version 1.4 supports resolutions up to 4096×2160, however, according to c't (German), the HDMI interface used with Intel chips only supports 1920×1200. The same goes for the DVI output – dual-link DVI-D, apparently, is not supported by Intel.
It would appear that my laptop cannot digitally drive this kind of resolution. Now what about other laptops?
According to the article in c't above, AMD's integrated graphics chips have the same limitation as Intel's.
NVIDIA graphics cards, apparently, only offer resolutions up to 1900×1200 over HDMI out of the box, but it's possible, when using Linux at least, to trick the driver into enabling higher resolutions. Is this still true? What's the situation on Windows and OSX?
I found no information on whether discrete AMD chips support ultra-high resolutions over HDMI.
Owners of laptops with (Mini) DisplayPort / Thunderbolt won't have any issues with displays this large, but if you're planning to go for a display with dual-link DVI-D input only (like the Korean ones), you're going to need an adapter, which will set you back something like €70-€100 (since the protocols are incompatible).
The big question mark in this equation is VGA: a lot of laptops have it, and I don't see any reason to think this resolution is not supported by the hardware (an oft-quoted figure appears to be 2048×1536@75Hz, so 2560×1440@60Hz should be possible, right?), but are the drivers likely to cause problems?
Perhaps more critically, you'd need a VGA to dual-link DVI-D adapter that converts analog to digital signals. Do these exist? How good are they? How expensive are they? Is there a performance penalty involved?
Please correct me if I'm wrong on any points.
In summary, what are the requirements on a laptop to drive an external LCD at 2560×1440, in particular one that supports dual-link DVI-D only, and what tools and adapters can be used to lower the bar?
Best Answer
I am successfully using a Korean 27" IPS display (Crossover 27Q) at 2560x1440@60Hz in Linux over a VGA cable, with an old (GM45) Intel chipset. To my surprise, the hardware can drive the image just fine at that resolution over VGA. The image is relatively sharp, but there are some "ringing" artifacts to the right of hard intensity transitions.
The most surprising thing though is that a second, brand new Belkin VGA cable I bought could not drive the monitor at full resolution. I don't know if it's because the first cable has those ferrous blocks on both ends to cancel RF noise, or if there is a wiring difference between the two cables, or if there is a difference in electrical characteristics of the wires, but the EDID of the monitor can't even be probed, so Linux doesn't know what modes the monitor supports with the Belkin cable, and will only drive it at a much lower resolution by default. I had no idea there was a difference between high-end and low-end cables.
I also tried the display with a Mid-2012 Macbook Pro with Intel HD 4000 graphics. The display only runs at 1920x1200 over both HDMI and DisplayPort-to-DVI with a Dual Link DVI cable. Apparently the chipset and the DisplayLink ports support 2560x1600 for Apple products, but not for third-party products. Probably running Linux or similar with HD 4000 you would have more luck.