October 2011 Update (OS X Lion 10.7.2): For 10.7.0 and 10.7.1, the pinstriping problems returned and are unavoidable. With 10.7.2, the unplug/replug workaround described below works again, at least for my 2010 Mini. However, users are still reporting problems with Snow Leopard and Lion when using other Dell UltraSharp monitors (i.e. u2412m). The problem appears to be the result of a conflict between the graphics driver's dithering system and the monitor's, as the affected displays tend to use Advanced Frame Rate Correction (A-FRC) to emulate 8-bit color from their 6-bit panels. After taking the mini to a Genius, he confirmed that the OS X driver is the likely culprit, and 'escalated' the problem with a note to the engineering team. Hopefully the engineers will address this permanently in the future, but until then, I recommend that anyone who experiences this problem take their Mac to the Genius Bar and have them submit the issue to engineering. ---original post below--- So after a good bit of troubleshooting, I have finally gotten my monitor to work with my Mac Mini. Hopefully by reporting my experience, this information will be beneficial to other Mini users. Bottom line: If you want to use the Dell UltraSharp u2211h with a Mac Mini, you must: 1) Use a Mini DisplayPort-->DisplayPort cable and 2) Leave the monitor powered off during boot, turning it on only after the login screen shows up. Otherwise, the monitor will display pinstriping artifacts on certain colors, and the computer may not wake from sleep. If you forget to turn the monitor off, unplugging and replugging the mini DisplayPort connector should fix the problem. For the full story, read on... Background: Why match a Dell monitor with an Apple computer? The LCD panels in Apple's displays use in-plane switching (IPS) technology, which gives them good color fidelity and wide viewing angles. However, for many users, these advantages are negated by the glossiness of Apple's panels, which can make it difficult, if not impossible, to enjoy the benefits of this high-end monitor technology. While IPS panels previously commanded a significant price premium over typical LCD displays, a new variant of the technology (e-IPS) has enabled vendors to offer IPS monitors for much lower prices. One of the companies taking advantage of e-IPS is Dell, which makes the UltraSharp u2211h, a monitor of the same size and resolution as the 21.5" iMac (1920x1080). This monitor sells for around $280 new ($200 refurbished via Dell's Outlet store) with a 3-year advance replacement, zero-dead-pixel warranty. Most important of all, however, is that the Dell monitor has a matte coating, much like the pre-aluminum iMacs and pre-unibody MacBook Pros. I acquired a refurbished unit direct from Dell, which had a few dead pixels. Thankfully, Dell had a flawless replacement at my door less than 24 hours after phoning in the problem. After years of groaning at the crummy quality of my 2006 iMac's screen, I was ready to be impressed. Problems (and solutions) with the u2211h on Macs Unfortunately, despite Apple's promise that you can hook up any old monitor to their Mac Mini, the u2211h does not play very well with some Macs under certain conditions. Hooking it up via DVI to the aforementioned 2006 iMac, I noticed that on certain solid colors, the monitor exhibited a very noticeable horizontal pinstriping effect. This effect was similar in appearance to the pinstriping we used to see throughout previous versions of OS X, except that now it was showing up on what were supposed to be solid colors! For certain shades of gray, the pinstripes became diagonal and started moving from right to left. This was completely unacceptable, but since I was in the process of upgrading to a new Mini, I just wrote off the problem as a symptom of an aging computer. Much to my dismay however, this same problem showed up on the brand-new 2010 Mini when using HDMI/DVI or Mini DisplayPort. Even worse, when hooked up via DisplayPort, the monitor would not wake up if it went to sleep, nor would the Mini itself wake up if it went to sleep! Frustrated, I was ready to throw it all out the window until I by chance discovered that if the DisplayPort cable was unplugged and then reinserted after the computer was booted, both the pinstriping and sleep/wake problems disappeared! After further experimentation, I found out that so long as I waited to turn on the monitor until the Mini finished booting (essentially until the login window appeared), the problems would never materialize. While the solution is less than ideal, I don't restart very often, so it's not much of a burden to keep the monitor off while booting. (Incidentally, the pinstriping/sleep/wake problems never show up in Windows 7, so there's no problem in turning the monitor on to access a Boot Camp partition from the EFI menu). For me, the present situation is much more desirable than a glossy monitor, so at the end of the day I am quite happy, enjoying my nice IPS matte display. Addendum: For what it's worth, while my 2006 iMac and 2010 Mini can both exhibit the pinstriping problem, it does not appear to affect all Macs. Just to satisfy my curiosity, I hooked up a 2007 MacBook with a GMA 950 (!) and there's no pinstriping whatsoever.