Intel Core i7 980X on three mainboards

INTEL'S LATEST Core i7 980X is the highest performance desktop PC CPU today, according to most benchmarks and application performance tests.

The only way up is to put together two Xeon varieties of this CPU, the X5680, for a twelve core beast which we covered in our exclusive EVGA SR2 tests last month. The 980X by itself is no slouch - six cores running at 3.33GHz, or 3.46GHz using Turbo, and 12MB shared L3 cache - while being compatible with the existing socket LGA1366 X58 chipset mainboards.

Here I tried this chip on what are possibly three of the best X58 mainboards around - Gigabyte X58A-UD7, the Asus P6X58D-E and the Asus Rampage III Extreme. While the performance differences using the same clock and memory settings between the boards were so minimal as to be almost indistinguishable, it was interesting to check how far they would overclock within reasonable settings and then pick an optimal setting for a couple of benchmarks.

All of these mainboards have been optimised from the ground up for massive overclocking. The incumbent record holder for many competitions, the Gigabyte X58A-UD7, seen below, has seen some "deep freeze" runs above 6GHz, and it is the only one of these three that provides a pre-built waterblock liquid cooling capability for the otherwise hot X58 chipset, or an alternative huge second-stage heat sink for the chipset if you're not a fan of liquid cooling.

The P6X58D-E, seen below, has Extreme Phase power drive for the CPUs.

And the Rampage III Extreme, shown below, the newest on the block, even has LN2-specific cooling operation switches.

All three of these boards have native USB3 and SATA3 interfaces, plus native SLI and Crossfire capability - at least three way, and four way in the case of the Rampage mainboard. The Gigabyte entry emphasises its 2oz copper and extra USB interface power supply, of course, while the Asus Rampage III has ROG Connect and ROG Station external overclocking consoles.

For the system platform, I used the Xigmatek Thor's Hammer high-end heatsink fan, which served us well in previous LGA1366 tests, as well as the Geil Black Dragon 6GB DDR3-2000 memory kit, the one without heatspreaders for better use of good airflow. For the Asus Rampage III Extreme, the black, compact yet sturdy Xigmatex Midgard W case was used. An Intel X25-M 160GB SSD was the storage.

With the sample Intel Core i7 980X in my hands, I tested a range of options, evaluating at what point the voltage jump required for more speed outweighs the benefits. The primary focus was on the CPU core speeds, while keeping the related uncore speed more or less around 3.2GHz for DDR3-1600, still the best compromise for 3-channel LGA1366 systems.

The first was the 3.33GHz default CPU core speed with DDR3-1600 memory, but lowering the voltage as much as possible for lower power 'green' standard operation. On the Gigabyte mainboard, as well as the Asus P6X58, we managed to get it running at 1.15V, while the Asus Rampage did need 1.16V - a small difference - to pass all the tests. The uncore ran at 1.25V in either case.

Then, we went for 4GHz (multiplier 30) CPU core speed, the known stable 'easy overclock' for most LGA1366 Extreme CPU parts. Both Asus boards were okay with 1.31V here, while the Gigabyte required 1.32V - again, a minor difference. In all three cases, the uncore was run at 1.3V.

Finally, I tried 4.4GHz (multiplier 33) CPU core speed, and it didn't make much sense. The voltage required to boot Windows and, at very least, run the Sandra 2010 CPU bench successfully, varied between 1.42V on the Rampage III and Gigabyte, to 1.43V on the P6X58D. As you can see, there was a gigantic voltage jump required here, with corresponding heat and power increases - not to mention long term lifespan reduction. So, I reverted to 4GHz as the ideal speed. Here are the test results, in this case on the Rampage III Extreme.

First, using the Asus HD5870 GPU, have a look at the 3DMark Vantage results. You might want to compare the CPU scores against the dual 4 GHz Xeon X5680 on the EVGA SR2 last month.

Then, the PC Mark Vantage 64-bit. The same applies, compare this versus the dual CPU EVGA with all else the same in the system.

Here is the Sandra test, CPU in HT mode.

In summary, these are great results at an acceptably low CPU voltage of around 1.32V, proving that 4GHz makes the best sense as the compromise option balancing extra overclocked performance with minimum added power and heat along with maximum CPU and system lifespan. In the follow-on parts, we'll look at more benchmarks and comparisons, including versus other Intel CPUs as well as an AMD Phenom II X6. µ