Practical Advice: Sandy Or Ivy Bridge?
We've now illustrated that Ivy Bridge dissipates its heat in a much smaller die than Sandy Bridge, and then uses a less effective mechanism for transferring it away from the die and out to a heat spreader. Once the overclocked processor's four cores are saturated, the temperature increase happens so fast that the CPU's thermal monitor triggers throttling faster than we could take and save a screen shot of Core Temp. The jump was phenomenal, taking less than a second from idle to throttling temperature. In the end, we had to use a script to take the shot.
Getting Rid Of Excess Heat
Our experience highlights one of the obstacles that prevents higher clock rates on Ivy Bridge-based CPUs: the cooling subsystem must be able to operate effectively and without any delay. On air, the throttling mechanism triggers before a cooling fan can spin up. We didn't have the luxury of risking the destruction of our test chips by prying their heat spreaders off, and we don't recommend that drastic step to anyone, really. So, we're recommending a closed-loop liquid cooling setup, at least. More extreme enthusiasts can pick a more serious cooling technology, of course.
We state without any hesitation: air-cooled Ivy Bridge-based processors cannot be overclocked as much as Sandy Bridge-based processors. Overclockers hunting for the latest and greatest overclockable processor, yearning for high-frequency overclocks, should keep that in mind. Maybe a Sandy Bridge-based chip is still the best choice, even in a world where Ivy Bridge exists.
If scalability isn't as big of a worry for you, Ivy Bridge is the more natural choice. Its performance per clock is a few percent higher, so long as you're looking at the same frequency from both architectures. After all, a 4.5 GHz Ivy Bridge-based CPU wins benchmarks against a Sandy Bridge processor at slightly higher clock rates. When you limit your overclock of a chip like the Core i7-3770K to 4.2 or 4.3 GHz, you’re completely on the safe side. There is no temperature issue, and performance remains impressive. Then again, such a system won’t be significantly faster than a machine running at its stock clocks.