Intel Lynnfield Core i5-750 & Core i7-870 Processor Review

Feature Test: Intel Turbo Boost - Turbocharged

For those of you who skipped the microarchitecture section, let's recap what Turbo Boost is, what it does, and how it is better than ever on Lynnfield.

Turbo Mode is an exciting feature that automatically unlocks additional speed bins (multipliers) and allows the processor to self-overclock based on thermal conditions and workload. For example, if the Power Control Unit (PCU) senses that only one core is active and the other three are in an idle state, it will use the unused power and thermal headroom to overclock that single active core to ensure superior single-threaded performance. Conversely, if you are running a multi-threaded application, the PCU will measure the thermal headroom and if the processor is running cool enough it will overclock all four cores. On the Core i7 Bloomfield chips, Turbo Mode could provide a 266Mhz speed boost in single-threaded workloads and 133Mhz in multi-threaded applications. However, for Lynnfield Intel have really kicked things up a notch. As we have all seen these last few months, Core i7 processors have a lot of overclocking headroom, which is testament to Intel's top-notch 45nm High K manufacturing process. With this in mind, Intel's engineers have put this substantial headroom to good use by giving Core i5-700 series processors 4 additional speed bins (up to 532Mhz faster) and Core i7-800 series model 5 additional speeds (up to 666Mhz faster).

Although the results will be fairly self-evident, let's check out the performance gains that Turbo Mode provides on the top-end Core i7-870 model. As per the above, thermal conditions permitting, it will run one core at 3.59GHz for single-threaded workloads, and anywhere between 3.06Ghz to 3.46Ghz in multi-threaded applications.

	Intel Core i7-870 Turbo Boost Off	Intel Core i7-870 Turbo Boost On	Performance Difference
Cinebench R10 64-bit: Single Thread	3853	4580	+19%
Cinebench R10 64-bit: Multi-Thread	16856	18115	+7%
HDxPRT	203	222	+9%
Lame Front-End	172s	144s	+19%
Photoshop CS4 64-bit	248.1s	206.1s	+20%
SuperPi 32M	781.592s	648.211s	+20%
WinRAR 3.8.0 Compression	200s	162s	+23%
x264 HD Benchmark	24.84 FPS	26.33 FPS	+6%
3DMark Vantage: CPU Score	18005	19543	+8%
Valve Particle Simulation Benchmark	142 Score	152 Score	+7%

As promised, the performance gains are there and they are substantial, ranging from 6-7% in highly multi-threaded applications to 20% in single-thread workloads. The performance gains that Turbo Boost provides are definitely nothing to scoff at, especially since they free and automatic which is ideal for less computer savvy users.

Now when you combine Turbo Boost with Hyper-Threading, you have two technologies that can work together to create some very noticeable performance improvements. Enough talking, time for some real benchmarks.