Can someone explain the concept of "turbo boosted" processors to me?

Can someone explain the concept of turbo boosted processors to me? Like if I have a 2.5GHz processor with a turbo up to 3.1GHz, what exactly does that mean? That it runs at 2.5GHz during normal computing but has the ability to speed up if need be? How long can a boost last? Why not just have the processor run at 3.1GHz all the time?

Thanks

 

It's based on load, number of cores being used, etc. It doesn't run at 3.1GHz all the time because it would run too hot. The CPU will lower performance based on temperature (and other parameters), although usually more than the rated 2.5GHz. It's designed to complete processes more quickly, although over time performance drops.

It's called "binning". Each CPU has rated speed, and then number of bins based on certain criteria. Each bin is rated at 133MHz or 100MHz increments. So a single or dual threaded app could have 6 bins of 100MHz so the 2.5 GHz would reach 3.1GHz, triple threaded app, 4 bins of 100Mhz so 2.5GHz could reach 2.9GHz, and four threaded app, 2 bins of 100Mhz so 2.5GHz could reach 2.7GHz. And amount of time it spends there is based on the temperature and other system parameters.

 

Single thread process benefit from high clock speed, which 1st gen quad core i7 Clarksfield could not achieve with all four cores. So Intel came out with Turbo concept to address this. The clock boost can last 20-60 seconds, subject to the TDP reached and the ability of the cooling system. Running at full boost permanently will throttle your CPU before you even realise it.

 

Actually, with clarksfield, you can run at the full turbo prescribed for the amount of cores used unless you go over the TDP or hit the temperature throttle, as far as i know, there is no time limit on clarksfield. Clarksfield CPUs aren't allowed to go over their TDP at all when they turbo. You can easily test this with a 920xm since you can set the maximum heat output allowed for the CPU. Lower it and you won't hit full turbo, increase it and you'll hit full turbo indefinitely as long as there is an appropriate load. This is somewhat hard to quantify when running on less than four cores since windows usually distributes the load across multiple cores if it's possible.

For SNB, it's different since the turbo is allowed to go over the TDP for a small amount of time and will throttle back to the max possible turbo within TDP afterwards.

 

You can change the CPU affinity for each process in Windows Task Manager, in order to force an application to run on one (or more, it's up to You) core only.

 

Unfortunately, many, many applications are still single threaded. Case in point: Many of the .NET Framework Windows Updates take about 10-20 minutes to apply even with an SB CPU and a fast SSD, because the patcher is single threaded.

 

Yeah, don't even get me going with that stupid .NET framework update.

 

This graphic should help

 

Turbo Mode(or Turbo Boost if you prefer) is a way to get extra performance without exceeding the power/thermal limits of systems that are power, thermal limited. Like laptops.

You can't run it at full speeds all the time because of that. But that's not too much of a problem as CPUs as so fast nowadays most applications finish executing before the time limit kicks in and the CPU can cool again.

As for the part where I put in Italics, yes, you are understanding it correctly.