UPDATE: After experiencing a similar problem with my Dell U2713HM, I’ve concluded that the real issue isn’t with the monitors, but with the cable length. Basically, try to avoid anything over 6 feet long for DVI-D.
I don’t normally write entire blog posts on the shortcoming(s) of a particular product, but when implementing a simple setup takes 3+ weeks* it’s probably a good idea to write about it so others don’t make the same mistake(s). The short story here is that the ASUS PA248Q doesn’t play well with (mDP -> DVI) active adapters, so don’t bother trying to use them with the it.
The particular setup I tried was AMD Radeon 7870 -> StarTech mDP to DVI active adapter -> DVI cable -> PA248Q. This worked for about 5 minutes, after which the monitor would repeatedly go in and out of sleep, claiming it detected no signal. No amount of input cycling or power cycling of both the monitor and PC helped. I wound up having to connect the PA248Q directly to my PC via DVI and then use the active adapter for a bizarre AMD Radeon HD 7870 -> mDP to DVI active adapter -> DVI to HDMI cable -> Dell S2240L connection for 1 of the remaining 2 monitors. I’m honestly shocked the latter worked with a consumer monitor while the supposedly professional grade PA248Q choked on an ostensibly simpler connection. The incompatibility is also disappointing considering AMD actively recommends the StarTech adapter.
Everything works now, got the PA248Q and 2 Dell S2240Ls up and running, but yeah … don’t use active adapters with the former.
I should point out that this is the only issue I’ve had with the ASUS, it’s been absolutely stellar otherwise.
*The simple setup I’m referring to is using 3 monitors with my Radeon HD 7870-equipped XPS 8500. The 1st week I bought the wrong cable. The 2nd week I bought the right cable but ran into the Radeon’s inability to support more than 2 non-DP monitors without using an active adapter. The 3rd week I tried the active adapter solution written above.