ZDNet has benchmarked the latest Thunderbolt-equipped iMac with a Promise Pegasus RAID with Thunderbolt and came away pretty impressed. Because out-of-the-box Thunderbolt RAID experience on new iMacs leaves a lot to be desired due to constrained RAM, author Robin Harris set himself up with a 16GB iMac. This isn’t a common scenario for average consumers, of course, but heavy-duty apps like Final Cut Pro benefit from as much memory as possible.

Harris used Blackmagic’s Disk Speed Test to pit a quad-core 2.66 GHz Mac Pro equipped with a 300GB 10k Velociraptor drive, 1GB ATI Radeon 5770 graphics card and 12GB RAM against a built-to-order 3.4 GHz Core i7 iMac with a 1TB hard drive, the standard 1 GB AMD Radeon HD 6970M video card and 16GB RAM. Both computers were benchmarked against a 4-drive Promise Pegasus Thunderbolt RAID that had both an empty array and more than a third full. The RAID performed pretty nice in both configurations…

The unit was able to sustain a 348 megabytes per second in real-life read/write performance, a pretty impressive feat.  “Thunderbolt works as advertised: fast and seamless. I plugged my 3rd HD display into the array with no problems”, he writes. It is speedy enough to handle full 1080p at maximum color depth and space, “and more in more common formats“. Too bad at least 8GB RAM is needed to enjoy these speeds, but the convenience and plug’n’play of Thunderbolt technology surely justify the $10 per gigabyte cost in non-Apple RAM modules. More about the benefits and fine print of Thunderbolt on your Mac in our detailed guide.

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