Intel Core i7-990X Extreme Edition Review

Written by Paul Goodhead

March 23, 2011 | 07:58

Tags: #990x #comparative #cpu #extreme #extreme-edition #i7 #lga1155 #lga1366 #overclocking #performance #premium #processor #top-end #x

Companies: #amd #intel

Performance Analysis

Given the frequency advantage the i7-990X has over the i7-980X, it was no surprise to see it edge out its older stable mate in all of our stock speed tests. In Cinebench 11.5, it was 0.25 points ahead of the i7-980X, a result that was mirrored by the slight 0.117 of a second advantage it demonstrated in WPrime. The i7-990X also demolished Intel's LGA1155 CPUs in these tests, thanks to its 12 processing threads.

Its higher stock clock speed and extra Turbo Boost headroom also meant that the i7-990X managed to get a slight lead over the i7-980X in our Media Benchmarks. Its overall score of 2,145 was 7 per cent faster than the 2,002 points of the i7-980X, which is an excellent result given the 4 per cent nominal clock speed advantage of the i7-990X.

However, the i7-990X faced stiff competition from the top-end Intel Sandy Bridge CPUs, only narrowly beating the i5-2500K and losing out to the i7-2600K - clearly Turbo Boost worked well on the new CPU.

Meanwhile, games showed less benefit from the extra clock speed on offer from the i7-990X, with Crysis showing no sign of a frame rate increase. This meant that the i7-990X lagged slightly behind the vastly cheaper LGA1155 based i5-2500K and i7-2600K.


*Intel Core i7-990X Extreme Edition Review Core i7-990X Performance Analysis and Conclusion
Click to enlarge

Overclocking

Next, we tried overclocking, starting with an aggressive 1GHz overclock, which the i7-990X easily took in its stride. Encouraged by this success, we continued to push the chip further, eventually settling on a stable overclock of 4.6GHz with a QPI of 200MHz and a 23x CPU multiplier.

This represents a 1.14GHz boost over the i7-990X's stock speed. The i7-990's overclock is also superior to the 1.07GHz stable overclock we achieved with the i7-980X. To stabilise this overclock, we had to pump 1.412V through the CPU, 1.96V and 1.375V through the CPU PLL and QPI/DRAM voltages respectively and 1.3V and 1.2V to the IOH and ICH.

We also had to set the UCLK frequency to 3,208MHz and the QPI link frequency to 7,218MT/s. We had the CPU happily booting at just under 4.8GHz, but couldn't get this overclock stable using air cooling; this is a good sign that there was still some headroom left in the chip that could be unlocked with more exotic methods of cooling.

At these speeds, the i7-990X demolished our test suite, clocking in record results in both Cinebench 11.5 and WPrime. We also saw a healthy 23 per cent increase in the CPU's overall Media Benchmarks score, with an impressive 2,645 points. However, the i5-2500K returned a score of 2,687 when overclocked, while the overclocked i5-2600K scored 2,702.

Meanwhile, the i7-990X's power consumption during our testing proved interesting, as it drew far less power than the i7-980X. This is due to the lower 1V vid of our sample, which places the CPU at the lower end of the range of vids with which LGA1366 CPUs ship.

*Intel Core i7-990X Extreme Edition Review Core i7-990X Performance Analysis and Conclusion
Click to enlarge

Conclusion

We lauded the i7-980X when it launched, as it justified its exorbitant price with its extra pair of cores and better overclocking potential compared with other LGA1366 CPUs. The i7-990X shares these features but enters a changed market, due to Intel's own LGA1155 CPUs.

The i5-2500K is roughly as quick as, and sometimes quicker than, the i7-990X in all but the most heavily multi-threaded tasks. It's also very overclockable, and considerably cheaper. As a result, only those running professional-grade multi-thread-optimised applications should consider the i7-990X, and even then, you'd be better off buying in an i7-980X, which is nearly as fast but £50 cheaper.

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