Intel Core i7 2600K & i5 2500K "Sandy Bridge" Review - PAGE 12

Power Consumption

To measure power usage, a Kill A Watt P4400 power meter was used. Note that the above numbers represent the power drain for the entire benchmarking system, not just the processors themselves. For the 'idle' readings we measured the power drain from the desktop, with no applications running; for the 'load' situation, we took the sustained peak power drain readings at the end of a 30 minute OCCT power supply benchmark.

The overall power rating for the Sandy Bridge chips is very good. Both the 2500K and 2600K require less power than any of the AMD X6 processors, and also use considerably less power than the Intel i7 920.

Conclusion

When the Sandy Bridge processors first entered our labs we were anticipating a substantial performance increase over the previous generation Core architecture, and to that end the 2500K and 2600K managed to not only meet our expectations, but also greatly exceed them. When looking at the performance of the 2600K in comparison to the LGA-1366 Core i7 920, the 2600K was able to handily outperform the older Nehalem architecture, and in some benchmarks it achieved nearly 40% better performance. On average the performance over the i7 920 was around 20% to 30%, which is very impressive considering a current high-end Nehalem (like the Core i7 950) sells for roughly the same price as the 2600K. This essentially means you get a 20% to 30% performance increase at no additional cost!

In addition to this, the Sandy Bridge CPUs also have a lower power envelope than Nehalem based processors, so you get more performance and better efficiency at the same price. However, taking into account that the core speed of the 2600K is higher than the 920, we overclocked the Nethalem processor for a better clock for clock comparison. With the Nehalem processor at 3.4GHz the performance gap was reduced, but the 2600K still had a 10% to 15% performance increase in most benchmarks.

The performance of the 2500K was also very impressive, but the reduced cache and lack of Hyper-threading slightly lowered the overall performance level. Still, the 2500K was able to compete aggressively with the AMD hexa-core processors, and in applications where multiple threads were not available it outperformed them quite easily. In other words, this allowed the 2500K to excel in the gaming portion of our benchmarks. Most modern games can only utilize up to four cores, so the 2500K's faster core speed over the competition from AMD and the older Intel Core architecture allowed it to perform second to only the 2600K in terms of gaming.

One aspect of the new Sandy Bridge architecture that is lacking in comparison to the LGA-1366 based processors is the memory bandwidth. This is due to the new processors using dual-channel memory architecture, as opposed to the triple-channel design used with Nehalem and Gulftown processors. However, even with dual-channel the memory bandwidth was able to exceed a rating of 20Gb/s, which wasn't far off from the performance of the processors that utilize triple channel. There was no real negative effect in the end, as the Sandy Bridge processors greatly exceeded the performance of the Nehalem based CPUs.

Since both of these processors are part of the K series, they include an unlocked multiplier which makes overclocking excessively easy. Both of the processors were capable of hitting speeds in the high 4GHz range, with the 2500K reaching 4689MHz and the 2600K scaling up to 4589MHz. To achieve these ratings, the core voltage had to set to a maximum 1.4V, but even with the increased voltage both the processors only managed to stray into the 70°C temperature range while under load. After the processors were overclocked they both achieved impressive performance scores across the benchmarks. This allowed the overclocked 2500K to outperform the AMD hexa-core processors, and gave the 2600K scores that could rival even the $950 980X!

With the 2500K and 2600K having a MSRP of $215 and $317 respectively, they are priced right and will make quite impact on the current CPU market. The only downside I can see to this launch is that brand new owners of an Intel LGA-1156 or LGA-1366 system might have a hard time shaking buyer’s remorse after looking at the performance comparisons.