Last Saturday, I attended the Intel Blogger Day and had a chance to see the Intel roadmap. At first, Intel introduced the new processor they’ve announced recently, Core i7. It contains numerous of technology to ensure everyone that Intel is the leader in this market; 45nm, QuickPath, and Turbo Mode. Since I haven’t interested to CPU technology for a really long time. I have no idea about these new technologies so I didn’t think I would have a question about this, at least until the speaker had presented about Intel Turbo mode.
Intel Turbo mode is something like the intelligent CPU frequency adjusting system. If your quad-core CPU knows that you’re using the CPU at 1 - 2 cores, it mights turn off the idle core in exchange of some frequency gain on the rest. For example, your 3.2 GHz quad-core CPU may turns itself into 3.4 ~ 3.6 GHz dual core CPU. The overall performance will be higher. In some circumstances, it can pushes itself a little without turning off the other core to gain another bit of performance gain.
Then my question arose, I asked the speaker why Intel don’t just make it in turbo mode all the time. I can remember when I was a hild, I always made my computer in the turbo mode. He answered me that because making the CPU runs in turbo mode consumes too much energy, generate too much heat and it will cost me a lot. So I replied him swiftly, “I can afford the energy cost. Then why?”. “It won’t meet the design specification”, he explained. I expected something more technically so this answer didn’t satisfy me but I stopped to ask for more information or I would be able to buy any Intel products. :P
Picture from PC Perspective.
After some googling, I found out how Turbo mode works and why Intel makes i7 be in the Turbo mode for just a short moment. The speaker was right. Firstly, It turns off some idle cores to give energy to the working cores instead so all cores cannot run in “Turbo State” consequently. Secondly, Turbo mode works like overclocking. Therefore, it cannot run in that state too long or it burns. Lastly, making all cores work in Turbo mode drains much more energy. And that amount is higher than that stated in the spec.
My question is answered. But new question arises, why doesn’t he explain this technically?
