One of the many websites I write for is PC Perspective, a computer hardware site for which I often times write laptop reviews. Recently I had the chance to throughly test a laptop equipped with a Core i7 640UM processor.
I was excited when I first began to fire up the benchmarks because I had high hopes for the processor. The Core i7 640UM is a low-voltage dual core processor with a base clock speed of 1.2 GHz, similar to the low clock speeds found on old Core 2 Duo low-voltage processors. However, the Core i7 640UM has TURBO BOOST!!! and, according to Intel specifications, it is able to ramp up to 2.26 GHz when needed.
If you’re not sure why that sounds pretty damned cool, let me explain. Power efficiency and performance are two objectives that have been at odds since the beginning of time. Processors that sip power, such as the Atom and Core 2 Duo CULV processors, are often slow. We’re not talking about a minor difference, either – a standard 2 GHz Core 2 Duo mobile processor is often times twice as quick as a Core 2 Duo CULV processor. Processors that perform well, like the Intel Core i7 quad-core, can rip through a sizable battery in two hours or less.
The Core i7 640UM seems like the best of both worlds. When you’re just being a douche at your local coffee shop by reading 4Chan and listening to music on your laptop speakers the processor can remain at a low clock speed, conserving energy. But when you head home and try to own fools in Call of Duty the processor will hit TURBO BOOST!!! and provide an outstanding experience.
That’s the theory, anyway – but reality disappoints.
During my tests I found that the Core i7 640UM is much slower than the standard Core i3 processor. In fact, the Core i7 640UM proved to be only somewhat quicker than the Core i3 380UM that I previously reviewed. The performance gap between the two processors was generally 20%, while the standard Core i3 was up to 50% quicker than the Core i7 640UM. This information is based off results I received using the SiSoft Sandra processor benchmarks.
This might make sense if Intel was selling the Core i7 640UM as a budget processor – but the laptop I tested was priced at over $1300. Even Acer’s 640UM-equipped TimeLineX model is priced at $850, which is higher than the price of TimeLineX laptops shipping with far quicker Core i3 and i5 processors. In other words, this is an expensive processor found in expensive laptops, and yet the performance it offers isn’t better than a processor you’ll find in laptops retailing for $600.
The question is – why? Because the Core i7 640UM was able to only slightly defeat the Core i3 380UM, which does not offer Turbo Boost, I suspected that Turbo Boost was the issue. To confirm, I loaded up CPU-Z and watched it while I ran my processor-centric SiSoft Sandra benchmarks again. What I found was telling. While the Core i7 640UM has a stated Turbo Boost maximum of 2.26 GHz, it never reached the speed. In fact, it didn’t come close. Instead it fluctuated between 1.4 GHz and 1.8 GHz (approximately) and spent most of its time in the 1.4 GHz to 1.6 GHz range.
I wanted to make sure this wasn’t an aberration associated with my benchmarks, so I also tried some other processor intensive tasks. I encoded some audio files with iTunes, I played World of Warcraft (windowed) and I ran OCCT, a program that is designed to stress-test processors. The results were the same with some fluctuations. During iTunes and World of Warcraft the processor spent more time around 1.8 GHz, while the more demanding processor stress test knocked it back down to hanging out at 1.4 GHz.
So when can the Core i7 640UM reach it’s Turbo Boost maximum? When you’re opening a program for the first time, like Firefox, or GIMP. That’s about it. Any period of sustained load quickly limits the processor to a speed of about 1.8 GHz or less.
Obviously, I’m not pleased with these results. When Intel introduced Turbo Boost there was some skepticism, because the Turbo Boost maximum is a vague metric. All it states is that a processor should be able to reach the Turbo Boost maximum at some point – but even this isn’t guaranteed. Intel isn’t going to take back a processor if you can’t make it reach its Turbo Boots maximum.
This initial skepticism faded when it turned out that the first round of processors did a good job of scaling up to their maximum Turbo Boost value, but it seems that – at least in the case of the Core i7 640UM – Intel is playing fast and loose with the numbers. Can the Core i7 640UM reach a speed of 2.26 GHz? Yes. Will it perform like a 2.26 GHz processor during any period of sustained load? Absolutely not.
Now please note, I’m not condemning Turbo Boost as a rule. It’s a great feature – but only if you can reach, or at least come close to, the maximum during some load situations. The Core i7 640 can’t. Instead, it runs about 400 Mhz lower than the stated Turbo Boost ceiling. As a result, the Core i7 640UM is not a good processor. It’s the first disappointing Intel processor I’ve tested since Atom was released. There is no reason to buy a laptop powered by this processor so long as you can buy Core i3 laptops with excellent battery life, such as the ASUS U33JC or the Acer TimeLineX products.
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