Leopard II: iMac video issues revealed

When we first tested Leopard, initial impressions of the new OS were very favorable, and many of these initial observations hold over after days of extended use. The OS continues to not just run quickly but also upgrades the performance of a few previously sluggish components, especially Spotlight. We've discovered a few pleasant upsides to Leopard since then; however, we've also found a few potential showstopping bugs that may have early adopters think twice.

The more we use Leopard, the more it becomes apparent that the most significant upgrades to Mac OS X may actually be its Internet-based features rather than Time Machine or even the reworked Finder. iChat is especially beneficial to anyone who regularly speaks with friends online using AIM (or, in some cases, Jabber); the organization of buddy lists and multiple chats is just as useful to any user as presentations and screen sharing are for business. Safari's on-page search tools and Dashboard's new widgets (including WebClip-generated widgets) are also handy for anyone finding a buried word in a large article or checking on movie showtimes.

Spaces may also be a far more useful addition than expected, particularly for users with small (or crowded) displays on notebooks; it eliminates the need to continually switch to and shuffle app windows and may let some MacBook users put off buying an extra screen if their workflow doesn't require too many immediately visible (but still important) programs.



However, we've encountered significant compatibility issues that might preclude some users from enjoying Leopard right away -- if at all.

Most of these appear to have their roots in the rough drivers for AMD's ATI Radeon HD video card series, which Apple has acknowledged is causing freezing issues for the newer iMacs that use it. Upgrading to Leopard doesn't resolve this issue, which will reportedly be fixed in the near future for both the new and old operating systems. Until then, however, backing up work may be a routine for iMac owners as the freezes often happen without warning.

In fact, the OS may also have added its own share of display-related issues that are typically absent in Tiger. While intermittent, we've seen brief instances of pixel artifacts around Dock icons and one instance of white "streaks" flying across the screen, which previously only appeared in a Boot Camp install of Windows.

More disconcerting are outright shutdowns of the video system in certain conditions, particularly when Mac OS X invokes a full-screen mode. We've seen instances of Front Row, Time Machine, and the third-party game Warcraft III all randomly turning the screen completely black; when this happens, the only choice is to restart the system entirely, even though background sounds reveal the OS itself is working properly behind the scenes. These issues are borderline unacceptable, particularly on a new iMac which is supposed to represent the best Leopard (and Apple as a whole) has to offer.

Still, if Apple can resolve these problems and it turns out that the issue hasn't spread to other Macs, the OS should still be a clear step forward for most users. As much as these features limit using Leopard as intended, it would be hard to step back to Tiger's comparatively basic feature set.