Does the Mac mini Really Need 512MB RAM With Tiger--How Fast Is It?

The requirements for running Mac OS X 10.4 "Tiger" list 512MB of RAM. So Apple has now increased the minimum amount of RAM across all models of Macs, desktops and laptops, from 256MB to 512MB. It's a nice bonus but was it really needed for a Mac mini?

We have shown previously that 256MB of RAM runs Mac OS X just fine, at least through 10.3.x "Panther," when running simultaneously a large number of applications that consumer-level Mac users might run on a 1.25GHz Mac mini. Not the professionals, mind you, who might be working with digital video and large images and RAM-hungry applications like Adobe Photoshop. We mean regular consumers who surf the Web, send email, write letters, do the home finances, listen to songs via iTunes or watch digital video via QuickTime Streaming, especially those entry-level Mac users who might buy a Mac mini.

Because of Tiger's 512MB RAM requirement, we decided to re-run our 1.25GHz Mac mini RAM tests using Mac OS X 10.4.2 to see if there is a difference between 256MB and 512MB of RAM that our test can determine using the new operating system. First, we ran Xbench 1.13 with no applications open except Xbench and without an internet connection to our Mac mini with 256MB and then with 512MB of RAM. Then we opened Safari, Mail, iTunes, Word 2004, Excel 2004, eight Dashboard Widgets and QuickTime simultaneously and also opened a feed of The Island movie trailer at medium resolution vis QuickTime/iTunes from thr iTunes Music Store. With the applications open we re-ran the Xbench tests at 256MB and 512MB of RAM.

Opening the applications causes a significant performance hit on the Mac mini as measured by Xbench. The idea of the test is to see if moving from 256MB RAM to 512MB of RAM in the Mac mini in any way ameliorates the performance hit.

Here is how RAM is allocated by Mac OS X 10.4.2 without the applications open and with them open under 256MB and 512MB of RAM.

Mac mini RAM Usage With and Without Apps Open
256MB
512MB
RAM Allocation
No Apps
Apps
No Apps
Apps
Wired
38
47
58
67
Active
69
137
64
262
Inactive
76
69
79
176
Subtotal Used
183
253
202
505
Free
73
3
311
7
Total
256
256
512
512

With no applications open, the RAM allocation among categories is very similar between 256MB and 512MB, with the extra amount being "Free." Opening the applications greatly increases the amount of "Active" RAM and there is virtually no free RAM left at either 256MB or 512MB.

Here are the speed test results with no applications open and with the applications open:

Xbench 1.1.3 Total Scores With and Without Apps Open*
256MB RAM
512MB RAM
Xbench Test with...
No Apps Open
135
138
Many Apps Open
103
103
*Average of 5 runs.

The Xbench scores running Tiger are virtually identical between those at 256MB and those at 512MB, just as we found when running Mac OS X 10.3.7 Panther. Therefore, adding the additional 256MB of RAM did nothing to ameliorate the performance hit caused by so many open applications and QuickTime streaming activity. In addition, The Island movie trailer looked just as smooth at 256MB as at 512MB while running the Xbench tests.

We continue to believe, based on this test and actual use, that 256MB of RAM is adequate for Mac OS X, including Tiger, for running basic consumer-type applications. But Apple is giving everyone who buys any Mac, including now the Mac mini, an extra 256MB for free. While some may prefer a discount, few are going to complain. [Bill Fox]



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