Intel Core i7 Mobile CPU (Clarksfield) Review
LAME MT and X264 Encoding
In our custom LAME MT MP3 encoding test, we convert a large WAV file to the MP3 format, which is a popular scenario that many end users work with on a day-to-day basis to provide portability and storage of their digital audio content. LAME is an open-source mid to high bit-rate and VBR (variable bit rate) MP3 audio encoder that is used widely around the world in a multitude of third party applications.
In this test, we created our own 223MB WAV file (a hallucinogenically-induced Grateful Dead jam) and converted it to the MP3 format using the multi-thread capable LAME MT application in single and multi-thread modes. Processing times are recorded below, listed in seconds. Shorter times equate to better performance.
The Core i7-920XM puts in a very strong showing on our LAME MT test, but its multi-threaded performance is still only on par with that of the 2.8GHz Core 2 Duo X9000-based Dell notebook. In fact, with the exception of the Core 2 Quad 9400, all of our comparisons systems were at least as fast as the Core i7-920XM or faster when it comes to multi-threaded performance on this encoding test. If you look at the scores, however, you will see that there is a very tight grouping here with very similar multi-threaded performance among them. There is a wider range of performance with the single-threaded encoding performance, and here the Core i7-920XM comes out on top--in part because the test's single-threaded workload enabled the CPU to scale up to 3.2GHz using Turbo Boost. Even though the Core i5-750 also scales up to 3.2GHz with Turbo Boost, the Core i5 processor lacks Hyper-Threading--which is what gives the Core i7-920XM the edge over the Core i5-750 here.
The x264 benchmark measures how fast a system can encode a short, DVD quality MPEG-2 video clip into a high-quality H.264 HD video clip. The application reports the compression results in frames per second for each pass of the video encoding process, and it is threaded so it can take advantage of the additional resources afforded by multi-core processors.
On this HD video encoding test, the Core i7-920XM was significantly faster that the 2.8GHz Core 2 Duo X9000-based Dell notebook. This is an indication that the new Core i7 Mobile platform should be much more efficient at encoding video than the Core 2 Duo processor--an increasingly important task for all platforms. On the other hand, all but one of the desktop-based CPUs handily beat the Core i7-920XM with their encoding speed. While the mobile processor may have come a long way in its performance capabilities, a modern desktop CPU is still the better choice when it comes to encoding video quickly.