Our review model, priced at $699 (as of August 6, 2012) as configured, sports an AMD Fusion A6-4455M processor, 4GB of RAM, a 500GB hard drive, and a 13.3-inch screen. It also offers 802.11a/b/g/n Wi-Fi, Bluetooth 4.0, and a built-in 1.3MP webcam. The Series 5 runs a 64-bit version of Windows 7 Home Premium.

Diehard AMD fans will be saddened to learn that the Series 5 NP535U3C doesn't quite match the performance of its Ultrabook counterparts. In PCWorld's WorldBench 7 benchmark tests, the Series 5 earned a rather puny 62 out of 100, meaning that it's speed was only 62 percent of our testing model's. The average WorldBench 7 score for the most recent three Ultrabooks we tested was 127.7.

To be fair, the WorldBench 7 tests take more than just processor speed into account, so components other than the AMD processor may share responsibility for the Series 5's poor showing. For instance, a major factor in WorldBench 7 tests is storage and startup speed; and one Ultrabook requirement is speedy boot-up times, which many Ultrabooks accomplish by using a small SSD caching drive plus Intel's Smart Response technology. This Series 5 doesn't have an SSD cache drive, so its startup time is comparatively slow (31.4 seconds versus 12.3 seconds for the much speedier ).

But some WorldBench 7 tests stress processor speed. In our Office Productivity tests, for example, the Series 5 managed a mark of just 950, while the Aspire S5 earned a score of 4039. And in our Web Performance tests, the Series 5 sustained 6.8 frames per second versus the Aspire S5's 12.8.