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Ivy Bridge overclocking performance is limited by current leakage

Analysis Great at 4GHz to 4.5GHz, but much more voltage needed beyond
Thu Apr 26 2012, 12:18
Intel Ivy Bridge processor

CHIPMAKER Intel has launched the upper end of its Ivy Bridge processor line, its first on the 22nm tri-gate process. Here is a look at the headroom of the first top end Ivy Bridge Core i7-3770K processor on Intel's Z77 chipset flagship mainboard, the D77GA-70K.

The Intel Core i7-3770K chip is rated at 3.5GHz or Turboboost up to 3.9GHz on all cores, and the D77GA-70K is likely Intel's best built gamer PC mainboard so far, both in component quality and I/O interface features.

The CPU is a multiplier-unlocked part, allowing theoretical overclocking all the way up to 6.3GHz without having to change the standard 100MHz base clock frequency - a move that normally crashes the system beyond 105MHz. Here we use an external GPU, so we don't have internal 3D benchmarks yet.

First of all, Intel has gone the way of Asus and other major mainboard vendors by implementing a GUI-based BIOS, here called "Visual BIOS". While it looks stylish and interesting to explore for a layman, its occassional hitches in saving the settings supposed to be saved and the duplication of functions in both 'basic' and 'advanced' modes will make expert users wish for the text-only menu option back. See the new menu look for yourself:

Having got past the settings saving problems, the choices for ideal performance enhancement with a good compromise between noticeable speed gain and minimal impact on reliability or lifetime of the CPU come up. I ran the system at a range of frequencies, from default all the way to 4.8GHz.

At about 4.4GHz, the voltage increases needed for fully stable operation that passed high load benchmarks started getting a bit steep. Basically, if we have 1V at the basic 3.5GHz level, and 1.2V at 4.4GHz, then we reach 1.3V at 4.6GHz and 1.4V at 4.8GHz, all plus Turboboost. Whether the high electrical leakage right now will be solved in the next stepping remains to be seen.

We wanted to see how far we could overclock the Ivy Bridge Core i7-3770K and keep its power usage below 100W. That number seems to be 4.4GHz with 1.25V for the CPU. This is with all the other settings including Turboboost left to default.


With the matching GEIL EVO 2X 2GB DDR3-2000 CL6-9-6 low latency memory running at DDR3-1866 CL7-8-7, an AMD Radeon HD6970 2GB GPU, and two SATA3 240 GB SSDs, an Intel 510 and a Corsair Force GT, whose performance on this new platform we will check separately, here are the Sandra and Cinebench results:

cine11newestIn summary, here you get a decent extra 25 per cent performance over the baseline, with a minimal, up to 30W, estimated system level power increase, or less than 10 per cent of an average discrete GPU equipped PC.

There seems to be a bit of an issue with pushing this CPU to very high levels using ordinary cooling - the sub-zero gang will have more luck as supposedly there is no 'cold bug' with Ivy Bridge anymore. But the ability to run everyday workloads on the box at 4.3GHz to 4.4GHz without hampering overall reliability and still keeping around 100W CPU power usage is definitely good news, showing the future potential of Intel's Ivy Bridge platform once an improved process appears in future steppings. µ


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