Vital Signs and Overclocking
Below are a couple of screenshots from the latest version of CPU-Z that detail some of the new Core i7-3770K processor’s inner-workings.
As you can see, the processor utilizes the same socket 1155 as Sandy Bridge, but the 3770K is built using Intel’s newer 22nm process node and has a TDP (Thermal Design Power) rating of just 77w. The chip we tested, and that will hit retail shelves, is stepping 9 and it features a stock 100MHz BCLK.
Because HyperThreading is supported and enabled, the Core i7-3770K can process up to 8 threads simultaneously on its 4 physical cores. Like previous generation Intel processors, SpeedStep and Turbo boost technologies are leveraged in the Core i7-3770K (and other 3rd Gen Core family of processors) that dynamically adjusts the CPU frequency up or down based on load. While idling, the Core i7-3770K stepped down to 1,600MHz (16x100MHz). Its base clock is 3.5GHz (35x100), however, and it can Turbo up to 3.9GHz (39x100) under load, power and thermals permitting.
The Core i7-3770K has 8MB of 16-way set associative Level 3 / LLC cache, which is shared amongst the CPU and graphics cores. The chip also has 1MB of L2 cache (4 x 256K, 8-way set associative) and 128K (4x32K) of L1 Data and 128K (4x32K) of L1 Instruction cache.
Like the Sandy Bridge-based second generation Intel Core processors, new Ivy Bridge-based processors offer limited flexibility when overclocking via BCLK manipulation. If you want to tweak CPU and memory frequencies via the BCLK, it can only be increased by a few MHz at a time. Intel claims about 7% in either direction, but that’s just a rough guideline--we've seen some go higher and some go lower.
Also like Sandy Bridge, processors based on Ivy Bridge have differing overclocking options enabled. K-series SKUs, like the Core i7-3770K we’re featuring here, are unlocked for easy overclocking via multiplier manipulation. But non-K SKUs will have “limited” unlocking which will allow for multipliers to be increased by up to 4 speed bins above the processor’s peak, official Turbo frequency. And processors that don’t offer Turbo, can only be overclocked by altering the BCLK. Now, while there’s not nearly as much BCLK headroom as previous architectures, that doesn’t mean it can’t be altered at all. As we’ve mentioned, there’s a bit of wiggle room there. As far as the other overclocking related features of Ivy Bridge go, above is a comparison comparing Sandy Bridge, Sandy Bridge-E, and Ivy Bridge. As you can see, Ivy Bridge supports the latest XMP memory reference code, more processor graphics ratios (up to 60), and CPU core multipliers up to 63.
We spent some time tweaking our Core i7-3770K using the stock Intel PIB cooler and an MSI Z77A-GD65 motherboard and were easily able to hit a rock-solid and perfectly stable peak frequency of 4.54GHz. We achieved this speed by increasing the CPU voltage to 1.25v, with a multiplier of 45 and a BCLK of 100.8MHz. With more tweaking, we're certain higher clocks will be possible. We were actually able to boot into Windows and run benchmarks at clocks above 4.8GHz, but our CPU was breaking the 90’C mark and throttling to keep temperatures in check. We should also mention that at the speeds we hit, with the stock cooler, temperatures were not an issue. While overclocked using a stock cooler, the 3770K idled in the high 40'C range and peaked in the low 80'C range.With such a small die though, thermal density may be an issue for overclockers. If you plan to overclock and Ivy Bridge chip, despite their relatively low-power consumption characteristics, you'll need a highly efficient cooler to pull heat away from the chip as fast as possible.
While we had the chip overclocked, we ran the multi-threaded Cinebench R11.5 benchmark to illustrate the kind of performance gains possible and were able to increase performance from the Core i7-3770K’s stock score of 7.41 to an impressive 9.09. The higher clocks we were able to achieve on the overclocked Core i7-3770K almost allowed it to overcome the two-core advantage of the Core i7-990X. Almost.