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Set Password Activation Time in Snow Leopard

In Snow Leopard, you can now set an amount of time after your Mac goes to sleep or engages the screen saver before it requires a password to log back on. In Leopard, the option was simply to require the password or not. Choose among several increments, between 5 seconds and 4 hours, from System Preferences > Security.

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Doug McLean



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Maxing Out Displays on the New Power Mac G5s

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When Apple released the new dual-core Power Mac G5 models, the company noted that a single Power Mac G5 can support eight displays. That can't be true, can it? After being blown away a few months ago when Apple sent Jeff Carlson two 30-inch Apple Cinema Displays for review (see photos at the two Flickr links below), we pictured a bright and no doubt high-temperature wall of the huge screens.

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If you upgrade the included GeForce 6600 to the $2,500 list price Quadro FX 4500 512 MB PCI Express card (a $1,600 upgrade at the Apple Store), you get two dual-link DVI adapters, which allows two 30-inch displays. The Power Mac G5 offers four PCI Express slots. Put a total of four Quadro FX's in and you can add... eight 30-inch displays. To get there, you'd need three more Quadro FX cards at $2,500 each, plus the single Quadro FX from the Apple Store (which limits you to one). Purchasing the cards, a Power Mac G5 Quad, and eight 30-inch displays would set you back a cool $32,500.

Can the Power Mac G5 really handle this? Unfortunately, no. Apple points out in a footnote, "Eight 20-inch or 23-inch Apple Cinema Displays can be connected to the Power Mac G5 using four NVIDIA GeForce 6600 graphics cards."

The issue is that the new PCI Express system has a specification known as "lanes," which is a measure of how much data the slot can carry. Each lane is about 250 megabytes per second (MBps). The Power Mac G5s have one 16-lane slot for graphics (4 GBps), one eight-lane slot (2 GBps) and two four-lane slots (1 GBps).

The GeForce 6600 can work with only four lanes, and so a Power Mac G5 can support four of those cards each with two smallish monitors (20- or 23-inch LCDs). The Quadro FX requires the full 16 lanes and two card slots.

How about 50? So I can't create an overwhelming video system in my office, but that doesn't mean others haven't tried... and succeeded. TidBITS stalwarts Joe Kissell and Dan Frakes both pointed me to HIPerWall, a project at the California Institute for Telecommunications and Technology. The HIPerWall (Highly Interactive Parallelized Display Wall) comprises 50 LCD panels for a total display surface of 23 by 9 feet (7.01 by 2.75 meters) and 200 million pixels. It's designed for earth sciences visualization, but will have biomedical and engineering applications, too. Twenty-five dual-2.7 GHz Power Mac G5s with 2 GB of RAM power two monitors each. They also have access to an aggregate of 10 TB of storage.


Based on the specs quoted for the HIPerWall system, I would guess that a second generation HIPerWall could use 13 Power Mac G5 Quads - each with 4 GB of RAM and powering four displays - to reduce the back-end footprint and lower costs slightly.


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