There's a lot of misinformation on this board about TDP ratings and many are in denial about the potential heat issues with Sandy Bridge. What many don't know is: 1) Intel's TDP rating significantly underrates maximum power consumption, 2) TurboBoost duty cycle is NOT included in the TDP rating, and 3) TurboBoost is causing heating problems in the MBP, which has better cooling capacity than the Air.
1) Misconception 1: TDP represents max power rating
From the Intel Datasheets:
“The TDP numbers are not indicative of the maximum power the processor can dissipate under worst case conditions.”
Intel is listing TDP numbers that are significantly lower than the actual maximum power draw of their CPUs. They are then relying on the fact that most applications barely use the CPU, assuming that it will remain idle most of the time.
http://www.silentpcreview.com/article169-page3.html
2) Misconception 2: Turbo-boost over-clocking is captured within the heat profile of TDP rating.
From Techreport on SB: The Turbo algorithm does something that may seem a little counterintuitive at first, allowing the CPU to ramp beyond its maximum TDP... taking advantage of the lag between when a relatively cool idle chip begins to warm up its environment.... the chip opportunistically pushes beyond its rated thermal peak by running at higher-than-usual frequencies within its Turbo Boost range. Once the surrounding system has warmed up or enough time has passed (the algorithm is complex, and Intel hasn't shared all of the details with us), the chip will drop back to operating within its TDP max... Turbo Boost algorithm incorporates not just the CPU cores but the IGP, as well; it can raise the operating frequency of the graphics processor when the CPU cores aren't at full utilization.
3) Misconception 3: SB heat issues in 2011 MBP won't appear in 2011 MBA
Since the Air ULV chips also use TurboBoost, expect the same thermal behavior as this poor MBP owner observes:
"I just ran my "old" 13 MBP (2010 edition - 2.66 GHz) and my day-old 13 MBP (2011 edition - 2.7 GHz) with identical conditions, and performed the same test on both: launch the game "Portal" and have it just sit on the main intro screen (which shows 3D graphics slowly panning around a room, plus the game's start menu).
On the 2010 MBP: CPU Temp: 149 F, Fan: 1999 rpm
On the 2011 MBP: CPU Temp 192 F, Fan: 6200 rpm
If I'm only running a simple application (like MS Word), the 2011 MBP actually runs a few degrees cooler than the 2010 system. However, as soon as the system is having to track a large number of open windows (whether those programs are graphically intensive or not), the CPU starts to heat up rather dramatically, and the fans ramp up to "jet turbine" mode.
With the Air's limited cooling capacity by virtue of it's case design, I expect SB heat problems to be worse than the MBP because it has less ability to respond to instantaneous heat caused by TB, even though it will be using the ULV chips. Also, keep in mind that the Intel's solution to prevent heat problems involves "throttling" the CPU through it's power control unit, but ALL major PC OEMs are experiencing throttling issues with SB!
1) Misconception 1: TDP represents max power rating
From the Intel Datasheets:
“The TDP numbers are not indicative of the maximum power the processor can dissipate under worst case conditions.”
Intel is listing TDP numbers that are significantly lower than the actual maximum power draw of their CPUs. They are then relying on the fact that most applications barely use the CPU, assuming that it will remain idle most of the time.
http://www.silentpcreview.com/article169-page3.html
2) Misconception 2: Turbo-boost over-clocking is captured within the heat profile of TDP rating.
From Techreport on SB: The Turbo algorithm does something that may seem a little counterintuitive at first, allowing the CPU to ramp beyond its maximum TDP... taking advantage of the lag between when a relatively cool idle chip begins to warm up its environment.... the chip opportunistically pushes beyond its rated thermal peak by running at higher-than-usual frequencies within its Turbo Boost range. Once the surrounding system has warmed up or enough time has passed (the algorithm is complex, and Intel hasn't shared all of the details with us), the chip will drop back to operating within its TDP max... Turbo Boost algorithm incorporates not just the CPU cores but the IGP, as well; it can raise the operating frequency of the graphics processor when the CPU cores aren't at full utilization.
3) Misconception 3: SB heat issues in 2011 MBP won't appear in 2011 MBA
Since the Air ULV chips also use TurboBoost, expect the same thermal behavior as this poor MBP owner observes:
"I just ran my "old" 13 MBP (2010 edition - 2.66 GHz) and my day-old 13 MBP (2011 edition - 2.7 GHz) with identical conditions, and performed the same test on both: launch the game "Portal" and have it just sit on the main intro screen (which shows 3D graphics slowly panning around a room, plus the game's start menu).
On the 2010 MBP: CPU Temp: 149 F, Fan: 1999 rpm
On the 2011 MBP: CPU Temp 192 F, Fan: 6200 rpm
If I'm only running a simple application (like MS Word), the 2011 MBP actually runs a few degrees cooler than the 2010 system. However, as soon as the system is having to track a large number of open windows (whether those programs are graphically intensive or not), the CPU starts to heat up rather dramatically, and the fans ramp up to "jet turbine" mode.
With the Air's limited cooling capacity by virtue of it's case design, I expect SB heat problems to be worse than the MBP because it has less ability to respond to instantaneous heat caused by TB, even though it will be using the ULV chips. Also, keep in mind that the Intel's solution to prevent heat problems involves "throttling" the CPU through it's power control unit, but ALL major PC OEMs are experiencing throttling issues with SB!
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