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Intel's Core i7-7700K CPU reached 7.3GHz using liquid nitrogen and liquid helium

Why it matters to you

This test shows how far Intel's new seventh-generation desktop processors can go, but only in extreme cooling conditions.

Prior to Intel’s reveal of its seventh-generation Kaby Lake desktop processors in early January, Asus held an Absolute Zero event challenging attendees to push the limits of those new Intel chips. German overclocker “der8auer” accepted the challenge and pushed the new Intel Core i7-7700K CPU to a clock speed of 7.3GHz (7,328MHz). That is rather high considering the chip has a max turbo speed of 4.5GHz right out of the box.

But don’t get excited and think your liquid-cooled system will enable the Core i7-7700K to break the 7.0GHz ceiling. Der8auer and his team used liquid nitrogen and liquid helium to set that new overclocking record. Typically, they use 79 to 132 gallons of liquid nitrogen per day during overclocking events, which costs around 30 to 40 cents per quart. By comparison, 26 gallons of liquid helium costs around $4,200, which lasts for only 15 minutes.

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“If you work constantly with [liquid helium], it lasts 15 minutes,” he said. “That’s quite funny if you calculate it. Liquid helium reacts different from liquid nitrogen because it’s lighter. The nitrogen we put into thermos flasks and fill it into the cooler, which is not working with helium. We have to fill the liquid helium with a lance directly from the original flask into the cooler where it shoots into the cooler and cools it down.”

Liquid helium is around 70 degrees Celsius lower in temperature than liquid nitrogen. However, it evaporates quickly, with one quart lasting around 10 seconds before it is gone. He said that once the lance is opened, they are spending $4.71 worth of liquid helium per second.

Of course, the expense came out of Asus’ pocket, but that is still rather expensive considering it is only being used to overclock a desktop processor. Thus, to make sure all those dollars weren’t for waste, the team had to make sure their plan was 100 percent perfect before deploying the expensive coolant.

Unfortunately, the achievement wasn’t accomplished without a few tragic losses along the way. Several processors lost their lives during the experiments because the team didn’t know how far they could increase the voltages. The chips’ sacrifice for the overclocking cause brought on their ultimate destruction due to the unknown effects of certain voltages.

The team initially overclocked the chip to 7.2GHz using liquid nitrogen with all four cores and eight threads online. He said they had the option to disable some of the cores and threads to reach a higher initial overclock speed, but he wanted to see the chip’s full potential. After saving the validation file, the team then introduced the liquid helium aspect into the overclocking setup.

“We cooled down the CPU to negative-248 degrees Celsius, which allowed me to overclock the CPU to 7,328MHz at four cores and eight threads,” he said. “This is the highest value ever reached by a four core Intel CPU. That was, of course, I would like to say, a milestone for me personally.”