Overclocking
Seeing as this is a K-Series chip we're evaluating, let's talk overclocking. In keeping with Sandy Bridge tradition, Ivy Bridge follows the path of limited BCLK headroom and plenty of room to manoeuvre on core ratio.
As depicted by the table above, the changes are small but designed to make it easier to overclock further.
Starting from the top, the maximum multiplier has been raised from 59 to 63 (in 100MHz steps), theoretically increasing the maximum speed on offer. Similarly, the IGP multiplier has been bumped from 57 to 60 (in 50MHz steps) and the highest supported memory frequency rises from 2,133MHz on Sandy Bridge to 2,667MHz on Ivy Bridge.
For those who do like to dabble with a little BCLK adjustment, Intel has also introduced a 200MHz memory strap (in addition to the existing 266MHz strap), making it easier to fine-tune memory speed.
Keeping things simple, here's our Core i7-3770K processor running with a standard 100MHz base clock and the multiplier cranked up to 48 - resulting, of course, in an operating frequency of 4.8GHz.
In the interests of full disclosure, we had to swap out the stock Intel cooler to a Corsair A70 equipped with a dual-fan configuration in order to hit this speed. Also, the CPU voltage had to be increased from default (circa 1.1V) to 1.35V in the BIOS. Even with this vastly upgraded cooler, the chip would hit 75ºC under load - perhaps the concentration of heat in the tiny 22nm transistors is proving to be too hot to handle.
The overclock isn't a bad return but we did expect more - as it stands, Sandy Bridge i7-2700K actually overclocks higher. Looking at the potentially-wider implications of this, we've heard that some PC builders are having trouble overclocking retail Ivy Bridge chips to speeds previously achievable by Sandy Bridge. System integrators may have problems matching the frequencies we've seen for the past year or so.
Given that Ivy Bridge isn't that much quicker than Sandy Bridge in CPU intensive tasks, this may well prove to be a headache that's difficult to get around.
With the overclock in place, the Core i7-3770K does a good job of beating itself up at the top of our single-threaded PiFast chart.
Putting all cores to work, we see sizeable gains in CineBench, too. The four-core, overclocked Ivy Bridge chip comes close to matching the six-core Goliath that is the $999 Core i7-3960X.
