Core i5-3570K, -3550, -3550S, And -3570T: Ivy Bridge Efficiency

Lining Up The Contenders: Are There 95 W IVBs?

The first issue to address popped up while I was working on my launch piece last month. Before Ivy Bridge-based processors were even showing up on shelves, we were already getting reports that Intel’s retail boxes were printed with 95 W TDPs, and not the 77 W limits the company tried claiming.

Intel responded with the following:

“Third-generation Intel quad-core standard power processors have a TDP of 77 W. In some cases, you may continue to see references to a 95 W TDP. Intel has requested that original equipment manufacturers continue to design platforms based on Intel 7-series Express chipsets to a 95 W TDP target to ensure compatibility with second-generation Intel processors.”

So, platforms continue to be designed to support 95 W Sandy Bridge-based parts, but Ivy Bridge is 77 W, right?

Technically, yes. However, Intel did seem to goof up. It should have been using a 77 W spec on its boxed processors. We received the following shortly after publishing our Core i7-3770K story:

The company seemingly used 95 W to indicate platform support, when it should have been citing the specification for the Ivy Bridge-based parts themselves. So, expect to see those five models (the -3550K should probably be -3570K) listed as 77 W parts moving forward.

Core i5-3570T: 45 W

From the bottom, Core i5-3570T is our lone 45 W sample. Intel achieves its aggressively low thermal ceiling by dropping the chip’s base clock to 2.3 GHz and only allowing Turbo Boost to kick up to 3.3 GHz on a single core when headroom allows for it. With four cores active, the chip is limited to 2.9 GHz.

Core i5-3550S: 65 W

A 65 W TDP gives the Core i5-3550S the flexibility to run at a more aggressive 3 GHz base clock rate. Turbo Boost subsequently pushes the chip up to 3.7 GHz when a single thread is active. With four cores taxing the CPU, frequency is dialed in at 3.3 GHz.

Core i5-3550: 77 W

Stepping up to the highest 77 W thermal ceiling opens up enough flexibility to operate the Core i5-3550 at 3.3 GHz. Turbo Boost facilitates an aggressive 3.7 GHz ceiling, which reflects really well in single-threaded applications. When all four of the chip’s cores are active, the -3550 runs at up to 3.5 GHz.

Core i5-3570K: 77 W

Flagship of the third-gen Core i5 family, Intel’s -3570K features a base clock rate of 3.4 GHz and a maximum Turbo Boosted frequency of 3.8 GHz. It achieves 3.6 GHz with cores active (and the available thermal headroom to not violate its TDP, of course).