Laptop users with a new system based on Intel's latest Core i5 and Core i7 chips may need to take care of what applications they choose to run when using it on battery power.
The Core i5 and i7 processors introduced at the start of 2010 ship with a feature called Turbo Boost technology, designed to improve performance. It does this by ramping up the clock speed of the processor whenever the operating system calls for maximum performance, as explained by this excerpt from Intel's web site;
"Intel Turbo Boost Technology is a way to automatically run the processor core faster than the marked frequency if the part is operating under power, temperature, and current specifications limits of the Thermal Design Power (TDP). This results in increased performance of both single and multi-threaded applications."
However, it turns out that that Turbo Boost does this even if the laptop is operating from battery power, which can dramatically shorten the battery life of the system, depending upon what it is being used for.
I found this out while testing some laptops for review that use the new Core i5 and Core i7 chips. In order to gauge battery life, I use a benchmark tool that keeps the system busy while simultaneously tracking how long the laptop has been running on battery power.
Few laptops live up to the vendor's claims on battery life (as a general rule of thumb, take the maker's quoted life and halve it), but one laptop in particular kept showing a battery score so much shorter than the specified figure that further investigation seemed appropriate.
Looking at the processor, I downloaded an application available from Intel, the Turbo Boost Monitor application, which gives a visual indication of when Turbo Boost is active.
Unfortunately, it was staying at this speed all the time, which seems to be the reason why the laptop was only able to last for about 1 hour 30 minutes on battery power, when the specifications quoted a life of up to 8 hours.
Sadly, Turbo Boost is not configurable by the end user. Some laptops may allow you to turn it on or off in the Bios, but this was not the case with the evaluation laptop in question.
Quoting from Intel's web site again;
"Intel Turbo Boost Technology is usually enabled by default by a switch in the Bios where you can either enable or disable operation. Other than this, there are no user controllable settings to change Intel Turbo Boost Technology operation either in the hardware settings or operating system. Once enabled, Intel Turbo Boost Technology works automatically under operating system control."
Of course, users should expect that running demanding applications will shorten battery life, but it is entirely possible that Turbo Boost will kick in if you are simply watching a DVD on your laptop, for example, and a battery life of 1 hour 30 minutes will not be long enough to see the entire movie in many cases.
So, while it may seem blindingly obvious that something like Turbo Boost would affect battery life, that just leaves the question of why on Earth Intel decided this would be a great feature for a laptop chip, and why is there no way to control its behaviour, other than disabling it in the Bios?
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