Tech Reaction

Recently, I was handed a large case marked “Mission: Unlock // Overclock” along with an envelop marked “Top Secret.” Intrigued, I opened the envelop to find a series of smaller envelops labeled with phase numbers. Proceeding with the mission, I opened the phase 1 envelop. Inside the envelop I found a USB key, aptly shaped like a key, accompanied by instructions to plug it into a computer.

Upon plugging the key in, I was greeted by a series of statements to complete and the option to generate a passcode. After completing the statements, I generated a passcode, removed the key from the computer and opened the phase 2 envelop. Phase 2 required placing the key with the passcode into the USB slot on the large case, pressing a button on the case and hoping I generated the correct passcode.

Luckily, I did generate the correct passcode and the case was now unlocked. When I opened the case, I could not believe what was inside: an Intel Core i7-875k, an IntelDP55SB Extreme Series, and two 4Gb kits of Patriot Viper II Series, Sector 5 Edition PC3-19200 (2400Mhz)

That brings us to phase three of the mission, using this unlocked version of Intel’s ultimate smart performer, Core i7.

The setup:

i7-875k
8GB PC3-19200*
Intel DP55SB
EVGA GTX 260 c216 (600/1458/1000, core/sp/mem)*
160GB Western Digital Caviar SE *OCZ ModXstream 700w*
Cooler Master Hyper 212+ with two Cooler Master R4-C2R-20AC-GP in push/pull configuration.
Win7 Pro x64*

*For comparison, I used a Core i7 920 (2.66Ghz) on an EVGA 3x SLI (E758) board along with these components.

Although a vital part of any computer, the CPU heat sink was not included in the case. I opted for this setup for two reasons, the first being that I could run out to MicroCenter and pick up the Hyper 212+ and two extra high CFM, low DB fans for a total of $30, and the second being that the Hyper 212+ cools like a beast. Originally, I had planned on liquid cooling, but after I got an 1156 retention bracket for my block, my pump died so I stuck with this setup throughout my testing.

A video overview of the unlocking portion of the mission:

Before taking a look at the performance, let’s look at the features of the i7-875k. The i7-875k sports 4 physical cores, 8 logical via Intel Hyper-Threading @ 2.93Ghz, 3.60Ghz with Turbo Boost enabled and 8Mb Smart Cache. Intel Turbo Boost Technology, which can be controlled in BIOS, dynamically changes processor frequency when working under specified power and thermal limits in order to provide a smoother computing experience. Hyper-threading allows you to run a up to 8 threads simultaneously increasing your productivity and the integrated memory controller supports dual channel DDR3 memory. This gem sure packs a powerhouse in a tiny package.

The “K” in the model number indicates that the processor is unlocked. What this means is that the processor has unlocked Turbo Boost multipliers, allowing for quick and easy overclocking as well as unlocked voltage and memory frequency. Pairing an unlocked processor with the Intel DP55Sb motherboard allows for full control of your computing experience. The highly tunable BIOS let you easily take advantage of unlocked multipliers, and overclock like mad.

On to the stressing, benching and overclocking.

A series of tests were ran on both the i7 920 and 875k at both stock speeds and at 4.0Ghz for comparison purposes. All test suites were left on stock settings.

3DMark Vantage
A standard in benchmarking. PhysX was left on as both processors were being tested with the same GTX 260 at the same speeds.

The 875k outscores the 920 at stock speeds. While they have the same total score at 4.0Ghz, the 875k has a higher CPU score.

Maxon Cinebench R11.5
The newest release of the popular Cinebench benchmarking suite which simulates what results you can expect using Maxon’s Cinema 4D suite. Great for multi-core CPU testing.

The 875k out performs the 920 at stock, and performs nearly as well at 4.0Ghz.

Fritz Chess
Testing how fast the CPU can calculate chess moves using a real chess game engine. Fully supports multi-core processors.

The 875k beats out the 920 at both stock speeds and 4.0Ghz.

Hyper Pi
Another favorite amongst overclockers and benchmarkers. Calculates how quickly the CPU can calculate Pi the 1m digits.

Although faster at stock speeds, the 875k is slower to calculate at 4.0Ghz.

POV Ray
Free CPU based ray tracing software. It has a built in benchmark for painless testing.

875k takes the cake in both cases.

ScienceMark
A cluster of real world, rather than synthetic, tests. Composite score is compared.

At stock speeds, the 875k scores significantly higher than the 920. At 4.0Ghz, the 920 marginally beats the 875k.

SiSoft Sandra
Although Sandra has a slew of synthetic tests, only a handful of the CPU tests were ran.

At stock, the 875k scores better in all tests, but it’s a toss up at 4.0Ghz.

Folding@Home
Real world folding results, running -smp 7 (A3 units) on the native windows client.

Although points vary by work unit, the A3 units all produce approximately the same points per day, give or take a few hundred. The 875k is the clear winner at stock speeds, but the 4.0Ghz crown is up for grabs.

Games
Games were ran at 1920×1080, and game preset high settings.

World in Conflict

Battlefield Bad Company 2

Gaming is a toss up, both the 920 and the 875k perform very well. 875K better in WIC, 920 better in BFBC2.

The performance of the i7-875k chip is impressive; it scores close to, or better than, the i7 920 in most tests and a games, but consumes much less power with a TDP of 95w and a max of 89 amps drawn. Since this in an unlocked chip, both the TDP max amperage can be changed in BIOS that support it. To me, that makes the 875k a clear winner.

Now for what everyone wants to see, overclocking these new i7-875k chips.

Here are two CPU-Z screen shots at stock speeds and default BIOS settings. These chips have a base clock of 133Mhz and multipliers of 9-22, 24 in turbo mode:

To show how easy it is to overclock this chip, let’s start with a video.

Okay, that was pretty good, but I know this chip can do better. Now, there are four different turbo multipliers, each corresponds to how many cores are being used. So if you want to hit different speeds or save power while using 1, 2, 3 or 4 cores you can. For my testing, I set all four multipliers the same to ensure I hit the speed I was looking for.

One thing to note, memory frequency is linked and synced with BClk, so if you want a higher RAM frequency, you will need to use a higher BClk, not a higher multiplier.

On to the overclocking fun.

First I decided I was going to keep the multipliers at the default 24 and just increase the base clock frequency. Increasing BClk to 180 yields a core speed of 4.325Ghz at 1.376 volts, not too bad on air!

How about just increasing the UNLOCKED multipliers? Well, I cheated a little on this one. I wanted to hit at least 4.3Ghz, but I was having trouble high multipliers, so I had to increase BClk by 2Mhz. Bumping up the multipliers to 32 and the BClk to 135 yields a clock speed of 4.324 @ 1.408volts.

My favorite method, increasing both BClk and unlocked multipliers. Setting the BClk at 162 and multipliers at 26 yields just over 4.2Ghz at 1.32 volts. With such low voltage, there is more overclocking headroom.

Considering these results were all on air, I am very impressed by this chip. It is, by far, the easiest processor I have overclocked. The unlocked multipliers really give it an edge over locked chips; having the option of mixing increased multipliers and base clocks provides and overall easier overclocking experience. Also note, overclocking varies from hardware to hardware, person to person. My experiences are not guaranteed reproducible.

Now that I have unlocked and overclocked, my mission has come to an end I can honestly say I love this processor. As a folder, I have been fond of the i7 920 for quite sometime now, but with the unlocked multipliers and power settings, I have found a new processor for my folding rig.

One thing that has not been mentioned yet, because it’s impossible to measure, is the overall smoothness of computing. For awhile, I have been noticing my 920 is a bit more jittery than I would like. A little lagging that is probably not that noticeable to most has really been bothering me, especially after switching between the 875k and the 920. The i7-875k is smooth as butter, I have not experienced any of the choppiness I have noticed with my 920.

All in all, the i7-875k is a keeper. I had been looking for a reason to move to the 1156 platform and now I have found it and couldn’t be happier.

Here’s your chance to get on the overclocking fun!

Intel has been kind enough to provide a similar set of hardware to give away to one lucky reader. It should be obvious what makes the i7-875k so special, but if you are unsure what it is, I will give you a hint. I have scrambled one word that describes the specialty of the i7-875k, you will have to unscramble it yourself, but it is easy! Here it is:

ueokcnld

Once you have it unscrambled, head over to the contest section of the forums for more details.

Disclaimer: Intel provided the i7-875k, DP55SB and kits of Patriot memory to be used in this review. They have also covered the cost of promotion of and prize for the contest in which one reader will win a similar package.