The modules have been installed in an iMac 21.5-inch (MD 509d / A) upgrade to the internal memory of 4 GB. In my iMac 2 Samsung RAM`s were installed, each with 2 GB ex works, the two 4 GB modules fit properly, the installation is done in 2 minutes. The chips were lt. System Profiler recognized immediately and referred to as "OK".
Whether the installation is actually needed is another matter, one should critically examine its applications. Necessary to expand storage for standard applications is probably not a possibly entering time loss it incurs when rendering a half-hour DVD, is probably only in a few minutes.
The iMac is fast for all of today's standard treatments enough, even when you render a video along with music in the background, open iPhoto and iMovie or iDVD he takes hardly 3 GB of memory (lt. Activity), since the upgrade something more like 5 GB. So with 8 GB you would already quite far.
But who knows what will be provided for system requirements from the nearest operating system ..., the memory devices (in addition to the dealer) are certainly worth the money.
