Whenever a new processor line gets released by Intel or AMD, the enthusiasts are usually the first to pick them up. As well as enjoying the increased stock performance, many also decide to overclock their chip to see how much extra performance can be squeezed out.
However, anyone who has overclocked a Sandy Bridge processor successfully may be in for a shock when they pick up an Ivy Bridge part. It has been discovered through testing that Ivy Bridge runs significantly hotter when overclocked. By significantly, I mean as much as 20 degrees Celsius more at the same clock speed.
The Tech Report did a real-world test where they pitted a Sandy Bridge Core i7-2600K against an Ivy Bridge Core i7-3770K. Both chips were pushed to 4.9GHz using air cooling and the results logged.
The power use was slightly higher for the 3770K (236w vs. 231w), voltages were almost the same, but again Ivy Bridge was a little higher (1.368V vs. 1.381V). Heat is where the two chips really differed, though. At 4.9GHz the Sandy Bridge chip held a steady 80 degrees Celsius, but Ivy Bridge was at 100 degrees Celsius. That may still be within operational limits, but suggests anyone wanting to run an overclocked Ivy Bridge is going to have to invest in some better cooling.
As for why there is such a big difference in temperatures, the culprit is most likely going to be the change Intel has made to the thermal interface. Sandy Bridge chips use a fluxless solder for the link between the CPU and the heat spreader.Ivy Bridge has switched to thermal paste, which is less efficient at dissipating heat.
Intel has confirmed the additional temperature is down to “different package thermal technology” and a “higher thermal density” for the Ivy Bridge chips. Neither of which are going to change,so if you intend to overclock one of these new chips, be sure to invest in rock solid cooling.
Yeah, 4,5GHz at stock volts is clearly a fail, especially looking at your 2600k you're running at 4GHz. The only reason why it 'fails' so much is that it can't be run at over 4,8GHz below 1,3v which effectively hits the thermal barrier on air cooling.
Saying it's worse than SB is wrong, plain and simple. It's just not worth the upgrade if you already have SB.