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We took our Core i7-4960X up to 4.7GHz on the Asus X79 Deluxe. That board's auto-tuning mechanism managed to overclock the CPU to 4.6GHz with little more than the click of a button, too. Let's see how the X79-UP4 and X79A-GD45 Plus compare.

Gigabyte got the first kick at the can. We started with EasyTune's auto-overclocking mechanism, which offers three QuickBoost levels with clock speeds based on testing done in Gigabyte's labs. For our Core i7-4760X, the most aggressive QuickBoost profile targeted 4.78GHz... and failed miserably. There was no video signal when the system rebooted, and we had to clear the CMOS manually to get things up and running again.

The second QuickBoost setting aimed for 4.53GHz, and it failed, too. The system rebooted without issue, but each attempt to load Windows produced a BSOD. At least the most conservative QuickBoost profile worked without issue. It turned the CPU up to 4.28GHz using a 42X multiplier and a 102MHz base clock, and that combo was stable under load.

Interestingly, the other QuickBoost profiles cranked the base clock to 103-104MHz. I suspect pushing that frequency caused the instability we encountered with those configs. Outside of officially supported gear ratios (100, 125, 167, and 250MHz for Ivy-E), the last few generations of Intel CPUs have offered very little base clock headroom.

Most auto-overclocking schemes rely on pre-baked profiles, but we prefer routines that slowly increase clock speeds and test for stability along the way. That's how we do things when overclocking manually, and the iterative approach yielded much better results on the UP4.

Through multiplier tweaking alone, we got our CPU up to 4.4GHz. The board supplied extra juice as necessary, but the automatic CPU voltage option was too conservative at 4.5GHz. That speed required a manual voltage bump to keep BSODs at bay under load. 4.6GHz wasn't stable no matter how many voltage and power settings we tweaked, though. Our load test, which combines AIDA64's CPU stress test with the Unigine Nature graphics benchmark, consistently crashed the system.

Next up: overclocking on the X79A-GD45 Plus. Again, we let the built-in intelligence have the first crack at the CPU. Pressing the OC Genie button on the circuit board loads up a pre-defined profile based on the system's CPU. For our Core i7-4960X, OC Genie picked a 43X multiplier and stuck with the default 100MHz base clock, yielding a 4.3GHz peak CPU frequency. This config was stable under load, so we started turning the screws manually.

Like on the Gigabyte board, the automatic voltage tuning worked through 4.4GHz. Higher speeds required manual adjustments. We also had to turn up the offset for CPU voltage droop. Those adjustments worked with the CPU running as fast as 4.6GHz. At 4.7GHz, however, the system consistently spit out BSOD errors under load. After playing with various voltage and power settings—with no success—we called it a day.

Power consumption
While testing the Gigabyte X79-UP4, we ran into an odd issue with our Ivy Bridge-E CPU. The system hard-locked after prolonged idling but was perfectly stable under load. Weird, huh? After much head scratching, trial, and error, we traced the problem to the CPU's C3, C6, and C7 sleep states. Disabling those sleep states in the firmware resolved the locking issues completely.

At first, we suspected the motherboard. The same CPU works just fine in the three other X79 motherboards we've plugged it into. But a replacement UP4 exhibited the same behavior, so we swapped the CPU for a fresh one from Intel. Problem solved.

Since we had already completed the bulk of our testing with the old CPU and its problematic sleep states turned off, we spot-checked the results with the new chip and all its power-saving mojo enabled. The two configs perform pretty much identically. There is a notable difference in power consumption, though. The results with the asterisk come from the new CPU.

We measured power draw at the wall socket with our test system at idle, then playing a 1080p YouTube video, and finally under a full load combining Cinebench rendering with the Unigine Valley demo.

With all the CPU's sleep states enabled, the Gigabyte board draws nearly 10W less at idle and almost 5W less during video playback. The savings only amount to a drop in the bucket on a typical monthly utility bill, but keep in mind that lower power consumption also means less heat for one's cooling system to expel.

We should note that Intel custom tunes the voltage ranges for Ivy Bridge-E CPUs. Our second sample runs at slightly higher voltages than the first one, but the differences are very small: 36 mV at idle and 12 mV under load.

But I digress. The real story here is the MSI X79A-GD45 Plus, which has the lowest power draw of the bunch. To be fair, it also has the fewest auxiliary peripheral chips. The others all have additional SATA controllers, and the Asus X79-Deluxe features built-in wireless connectivity and extra USB 3.0 chips, too. Peripheral controllers don't consume that much power, though. Asus' X79 boards have a history of higher power consumption, and that trend continues with Ivy Bridge-E.